What is "lead"

Lead \Lead\ (l[e^]d), n. [OE. led, leed, lead, AS. le['a]d; akin to D. lood, MHG. l[=o]t, G. loth plummet, sounding lead, small weight, Sw. & Dan. lod. [root]123.]

1. (Chem.) One of the elements, a heavy, pliable, inelastic metal, having a bright, bluish color, but easily tarnished. It is both malleable and ductile, though with little tenacity, and is used for tubes, sheets, bullets, etc. Its specific gravity is 11.37. It is easily fusible (melting point 327.5[deg] C), forms alloys with other metals, and is an ingredient of solder and type metal. Atomic number 8

2. Atomic weight, 207.2. Symbol Pb (L. Plumbum). It is chiefly obtained from the mineral galena, lead sulphide. 2. An article made of lead or an alloy of lead; as:

   1. A plummet or mass of lead, used in sounding at sea.

   2. (Print.) A thin strip of type metal, used to separate lines of type in printing.

   3. Sheets or plates of lead used as a covering for roofs; hence, pl., a roof covered with lead sheets or terne plates.

      I would have the tower two stories, and goodly leads upon the top.
      --Bacon

3. A small cylinder of black lead or graphite, used in pencils. Black lead, graphite or plumbago; -- so called from its leadlike appearance and streak. [Colloq.] Coasting lead, a sounding lead intermediate in weight between a hand lead and deep-sea lead. Deep-sea lead, the heaviest of sounding leads, used in water exceeding a hundred fathoms in depth. --Ham. Nav. Encyc. Hand lead, a small lead use for sounding in shallow water. Krems lead, Kremnitz lead [so called from Krems or Kremnitz, in Austria], a pure variety of white lead, formed into tablets, and called also Krems white, or Kremnitz white, and Vienna white. Lead arming, tallow put in the hollow of a sounding lead. See To arm the lead (below). Lead colic. See under Colic. Lead color, a deep bluish gray color, like tarnished lead. Lead glance. (Min.) Same as Galena. Lead line

   1. (Med.) A dark line along the gums produced by a deposit of metallic lead, due to lead poisoning.

   2. (Naut.) A sounding line. Lead mill, a leaden polishing wheel, used by lapidaries. Lead ocher (Min.), a massive sulphur-yellow oxide of lead. Same as Massicot. Lead pencil, a pencil of which the marking material is graphite (black lead). Lead plant (Bot.), a low leguminous plant, genus Amorpha ( Amorpha canescens), found in the Northwestern United States, where its presence is supposed to indicate lead ore. --Gray. Lead tree.

      1. (Bot.) A West Indian name for the tropical, leguminous tree, Leuc[ae]na glauca; -- probably so called from the glaucous color of the foliage.

      2. (Chem.) Lead crystallized in arborescent forms from a solution of some lead salt, as by suspending a strip of zinc in lead acetate.

         Mock lead, a miner's term for blende.

         Red lead, a scarlet, crystalline, granular powder, consisting of minium when pure, but commonly containing several of the oxides of lead. It is used as a paint or cement and also as an ingredient of flint glass.

         Red lead ore (Min.), crocoite.

         Sugar of lead, acetate of lead.

         To arm the lead, to fill the hollow in the bottom of a sounding lead with tallow in order to discover the nature of the bottom by the substances adhering.
         --Ham. Nav. Encyc.

         To cast the lead, or To heave the lead, to cast the sounding lead for ascertaining the depth of water.

         White lead, hydrated carbonate of lead, obtained as a white, amorphous powder, and much used as an ingredient of white paint.

Lead \Lead\ (l[e^]d), v. t. [imp. & p. p. Leaded; p. pr. & vb. n. Leading.]

1. To cover, fill, or affect with lead; as, continuous firing leads the grooves of a rifle.

2. (Print.) To place leads between the lines of; as, to lead a page; leaded matter.

Lead \Lead\, v. i.

1. To guide or conduct, as by accompanying, going before, showing, influencing, directing with authority, etc.; to have precedence or pre["e]minence; to be first or chief; -- used in most of the senses of lead, v. t.

2. To tend or reach in a certain direction, or to a certain place; as, the path leads to the mill; gambling leads to other vices.

   The mountain foot that leads towards Mantua.
   --Shak.

   To lead off or To lead out, to go first; to begin; as, Mickey Mantle led off in the fifth inning of the game.

Lead \Lead\ (l[=e]d), v. t. [imp. & p. p. Led (l[e^]d); p. pr. & vb. n. Leading.] [OE. leden, AS. l[=ae]dan (akin to OS. l[=e]dian, D. leiden, G. leiten, Icel. le[imac][eth]a, Sw. leda, Dan. lede), properly a causative fr. AS. li[eth]an to go; akin to OHG. l[imac]dan, Icel. l[imac][eth]a, Goth. lei[thorn]an (in comp.). Cf. Lode, Loath.]

1. To guide or conduct with the hand, or by means of some physical contact or connection; as, a father leads a child; a jockey leads a horse with a halter; a dog leads a blind man.

   If a blind man lead a blind man, both fall down in the ditch.
   --Wyclif (Matt. xv. 14.)

   They thrust him out of the city, and led him unto the brow of the hill.
   --Luke iv. 29.

   In thy right hand lead with thee The mountain nymph, sweet Liberty.
   --Milton.

2. To guide or conduct in a certain course, or to a certain place or end, by making the way known; to show the way, esp. by going with or going in advance of. Hence, figuratively: To direct; to counsel; to instruct; as, to lead a traveler; to lead a pupil. The Lord went before them by day in a pillar of a cloud, to lead them the way. --Ex. xiii. 2

   1. He leadeth me beside the still waters.
      --Ps. xxiii.

   2. This thought might lead me through the world's vain mask. Content, though blind, had I no better guide.
      --Milton.

3. To conduct or direct with authority; to have direction or charge of; as, to lead an army, an exploring party, or a search; to lead a political party.

   Christ took not upon him flesh and blood that he might conquer and rule nations, lead armies, or possess places.
   --South.

4. To go or to be in advance of; to precede; hence, to be foremost or chief among; as, the big sloop led the fleet of yachts; the Guards led the attack; Demosthenes leads the orators of all ages.

   As Hesperus, that leads the sun his way.
   --Fairfax.

   And lo ! Ben Adhem's name led all the rest.
   --Leigh Hunt.

5. To draw or direct by influence, whether good or bad; to prevail on; to induce; to entice; to allure; as, to lead one to espouse a righteous cause.

   He was driven by the necessities of the times, more than led by his own disposition, to any rigor of actions.
   --Eikon Basilike.

   Silly women, laden with sins, led away by divers lusts.
   --2 Tim. iii. 6 (Rev. Ver.).

6. To guide or conduct one's self in, through, or along (a certain course); hence, to proceed in the way of; to follow the path or course of; to pass; to spend. Also, to cause (one) to proceed or follow in (a certain course).

   That we may lead a quiet and peaceable life.
   --1 Tim. ii. 2.

   Nor thou with shadowed hint confuse A life that leads melodious days.
   --Tennyson.

   You remember . . . the life he used to lead his wife and daughter.
   --Dickens.

7. (Cards & Dominoes) To begin a game, round, or trick, with; as, to lead trumps; the double five was led.

   To lead astray, to guide in a wrong way, or into error; to seduce from truth or rectitude.

   To lead captive, to carry or bring into captivity.

   To lead the way, to show the way by going in front; to act as guide.
   --Goldsmith.

Lead \Lead\, n.

1. The act of leading or conducting; guidance; direction; as, to take the lead; to be under the lead of another.

   At the time I speak of, and having a momentary lead, . . . I am sure I did my country important service.
   --Burke.

2. Precedence; advance position; also, the measure of precedence; as, the white horse had the lead; a lead of a boat's length, or of half a second.

3. (Cards & Dominoes) The act or right of playing first in a game or round; the card suit, or piece, so played; as, your partner has the lead.

4. An open way in an ice field.
   --Kane.

5. (Mining) A lode.

6. (Naut.) The course of a rope from end to end.

7. (Steam Engine) The width of port opening which is uncovered by the valve, for the admission or release of steam, at the instant when the piston is at end of its stroke.

   Note: When used alone it means outside lead, or lead for the admission of steam. Inside lead refers to the release or exhaust.

8. (Civil Engineering) the distance of haul, as from a cutting to an embankment.

9. (Horology) The action of a tooth, as a tooth of a wheel, in impelling another tooth or a pallet.
   --Saunier.

10. (Music.)

    1. The announcement by one voice part of a theme to be repeated by the other parts.

    2. A mark or a short passage in one voice part, as of a canon, serving as a cue for the entrance of others.

11. In an internal-combustion engine, the distance, measured in actual length of piston stroke or the corresponding angular displacement of the crank, of the piston from the end of the compression stroke when ignition takes place; -- called in full

    lead of the ignition. When ignition takes place during the working stroke the corresponding distance from the commencement of the stroke is called

    negative lead.

12. (Mach.) The excess above a right angle in the angle between two consecutive cranks, as of a compound engine, on the same shaft.

13. (Mach.) In spiral screw threads, worm wheels, or the like, the amount of advance of any point in the spiral for a complete turn.

14. (Elec.)

    1. The angle between the line joining the brushes of a continuous-current dynamo and the diameter symmetrical between the poles.

    2. The advance of the current phase in an alternating circuit beyond that of the electromotive force producing it.

15. (Theat.) A role for a leading man or leading woman; also, one who plays such a role.

16. The first story in a newspaper or broadcast news program.

17. an electrical conductor, typically as an insulated wire or cable, connecting an electrical device to another device or to a power source, such as a conductor conveying electricity from a dynamo.

18. (Baseball) the distance a runner on base advances from one base toward the next before the pitch; as, the long lead he usually takes tends to distract the pitchers.

    Lead angle (Steam Engine), the angle which the crank maker with the line of centers, in approaching it, at the instant when the valve opens to admit steam.

    Lead screw (Mach.), the main longitudinal screw of a lathe, which gives the feed motion to the carriage.

"to guide," Old English lædan "cause to go with one, lead, guide, conduct, carry; sprout forth; bring forth, pass (one's life)," causative of liðan "to travel," from Proto-Germanic *laidjan (cognates: Old Saxon lithan, Old Norse liða "to go," Old High German ga-lidan "to travel," Gothic ga-leiþan "to go"), from PIE *leit- "to go forth."\n

\nMeaning "to be in first place" is from late 14c. Sense in card playing is from 1670s. Related: Led; leading. Lead-off "commencement, beginning" attested from 1879; lead-in "introduction, opening" is from 1928.

c.1300, "action of leading," from lead (v.1). Meaning "the front or leading place" is from 1560s. Johnson stigmatized it as "a low, despicable word." Sense in card-playing is from 1742; in theater, from 1831; in journalism, from 1912; in jazz bands, from 1934.

early 15c., "to make of lead," from lead (n.1). Meaning "to cover with lead" is from mid-15c. Related: Leaded (early 13c.); leading.

heavy metal, Old English lead, from West Germanic *loudhom (cognates: Old Frisian lad, Middle Dutch loot, Dutch lood "lead," German Lot "weight, plummet"). The name and the skill in using the metal seem to have been borrowed from the Celts (compare Old Irish luaide), probably from PIE root *plou(d)- "to flow."\n

\nFigurative of heaviness since at least early 14c. Black lead was an old name for "graphite," hence lead pencil (1680s) and the colloquial figurative phrase to have lead in one's pencil "be possessed of (especially male sexual) vigor," attested by 1902. Lead balloon "a failure," American English slang, attested by 1957 (as a type of something heavy that can be kept up only with effort, from 1904). Lead-footed "slow" is from 1896; opposite sense of "fast" emerged 1940s in trucker's jargon, from notion of a foot heavy on the gas pedal.

Etymology 1 n. 1 (context uncountable English) A heavy, pliable, inelastic metal element, having a bright, bluish color, but easily tarnished; both malleable and ductile, though with little tenacity. It is easily fusible, forms alloys with other metals, and is an ingredient of solder and type metal. Atomic number 82, symbol Pb (from Latin ''plumbum''). 2 (context countable English) A plummet or mass of lead attached to a line, used in sounding depth at sea or (context dated English) to estimate velocity in knots. 3 A thin strip of type metal, used to separate lines of type in printing. 4 (context uncountable typography English) Vertical space in advance of a row or between rows of text. Also known as ''leading''. 5 Sheets or plates of lead used as a covering for roofs. 6 (context plural '''leads''' English) A roof covered with lead sheets or terne plates. 7 (context countable English) A thin cylinder of black lead or plumbago (graphite) used in pencils. 8 (context slang English) bullet; ammunition. vb. 1 (context transitive English) To cover, fill, or affect with lead; as, continuous firing leads the grooves of a rifle. 2 (context transitive printing historical English) To place leads between the lines of. 3 (context transitive climbing English) lead climb. Etymology 2

1. (context not comparable English) foremost. n. 1 (context uncountable English) The act of leading or conducting; guidance; direction, course; as, to take the lead; to be under the lead of another. 2 (context uncountable English) Precedence; advance position; also, the measure of precedence; as, the white horse had the lead; a lead of a boat’s length, or of half a second; the state of being ahead in a race; the highest score in a game in an incomplete game. v

2. 1 (label en heading transitive) ''To guide#Verb or conduct#Verb.'' 2 # To guide or conduct with the hand, or by means of some physical contact connection. 3 # To guide or conduct in a certain course, or to a certain place or end, by making the way known; to show the way, especially by going with or going in advance of, to lead a pupil; to guide somebody somewhere or to bring somebody somewhere by means of.instructions. Hence, figuratively: To direct; to counsel; to instruct; as, to lead a traveler. Etymology 3

   vb. (misspelling of led English)

1. n. a soft heavy toxic malleable metallic element; bluish white when freshly cut but tarnishes readily to dull gray; "the children were playing with lead soldiers" [syn: Pb, atomic number 82]

2. an advantage held by a competitor in a race; "he took the lead at the last turn"

3. evidence pointing to a possible solution; "the police are following a promising lead"; "the trail led straight to the perpetrator" [syn: track, trail]

4. a position of leadership (especially in the phrase `take the lead'); "he takes the lead in any group"; "we were just waiting for someone to take the lead"; "they didn't follow our lead"

5. the angle between the direction a gun is aimed and the position of a moving target (correcting for the flight time of the missile)

6. the introductory section of a story; "it was an amusing lead-in to a very serious matter" [syn: lead-in]

7. an actor who plays a principal role [syn: star, principal]

8. (baseball) the position taken by a base runner preparing to advance to the next base; "he took a long lead off first"

9. an indication of potential opportunity; "he got a tip on the stock market"; "a good lead for a job" [syn: tip, steer, confidential information, wind, hint]

10. a news story of major importance [syn: lead story]

11. the timing of ignition relative to the position of the piston in an internal-combustion engine [syn: spark advance]

12. restraint consisting of a rope (or light chain) used to restrain an animal [syn: leash, tether]

13. thin strip of metal used to separate lines of type in printing [syn: leading]

14. mixture of graphite with clay in different degrees of hardness; the marking substance in a pencil [syn: pencil lead]

15. a jumper that consists of a short piece of wire; "it was a tangle of jumper cables and clip leads" [syn: jumper cable, jumper lead]

16. the playing of a card to start a trick in bridge; "the lead was in the dummy"

17. [also: led]

1. v. take somebody somewhere; "We lead him to our chief"; "can you take me to the main entrance?"; "He conducted us to the palace" [syn: take, direct, conduct, guide]

2. result in; "The water left a mark on the silk dress"; "Her blood left a stain on the napkin" [syn: leave, result]

3. tend to or result in; "This remark lead to further arguments among the guests"

4. travel in front of; go in advance of others; "The procession was headed by John" [syn: head]

5. cause to undertake a certain action; "Her greed led her to forge the checks"

6. stretch out over a distance, space, time, or scope; run or extend between two points or beyond a certain point; "Service runs all the way to Cranbury"; "His knowledge doesn't go very far"; "My memory extends back to my fourth year of life"; "The facts extend beyond a consideration of her personal assets" [syn: run, go, pass, extend]

7. be in charge of; "Who is heading this project?" [syn: head]

8. be ahead of others; be the first; "she topped her class every year" [syn: top]

9. be conducive to; "The use of computers in the classroom lead to better writing" [syn: contribute, conduce]

10. lead, as in the performance of a composition; "conduct an orchestra; Bairenboim conducted the Chicago symphony for years" [syn: conduct, direct]

11. pass or spend; "lead a good life"

12. lead, extend, or afford access; "This door goes to the basement"; "The road runs South" [syn: go]

13. move ahead (of others) in time or space [syn: precede] [ant: follow]

14. cause something to pass or lead somewhere; "Run the wire behind the cabinet" [syn: run]

15. preside over; "John moderated the discussion" [syn: moderate, chair]

16. [also: led]

Lead has two different pronunciations and several different meanings, usually related to either the chemical element lead (a heavy metal) or the verb to lead.

A lead in hydrocarbon exploration, is a subsurface structural or stratigraphic feature with the potential to have entrapped oil or natural gas. When exploring a new area, or when new data becomes available in existing acreage, an explorer will carry out an initial screening to identify possible leads. Further work is then concentrated on the leads with the intention to mature at least some of them into drillable prospects.

Lead is a Japanese hip-hop group, under the Record of Pony Canyon/ Flight Master. Their debut was on July 31, 2002 with their single Manatsu no Magic (Mid-Summer Magic).

Lead is a chemical element in the carbon group with symbol Pb (from ) and atomic number 82. It is a soft, malleable and heavy post-transition metal. Freshly cut, solid lead has a bluish-white color that soon tarnishes to a dull grayish color when exposed to air; the liquid metal has shiny chrome-silver luster. Lead has the highest atomic number of any non- radioactive element (two radioactive elements, namely technetium and promethium, are lighter), although the next higher element, bismuth, has one isotope with a half-life that is long enough (over one billion times the estimated age of the universe) to be considered stable. Lead's four stable isotopes each have 82 protons, a magic number in the nuclear shell model of atomic nuclei. The isotope lead-208 also has 126 neutrons, another magic number, and is hence double magic, a property that grants it enhanced stability: lead-208 is the heaviest known stable nuclide.

Lead is used in building construction, lead-acid batteries, bullets and shot, weights, as part of solders, pewters, fusible alloys, and as a radiation shield.

If ingested or inhaled, lead and its compounds are poisonous to animals and humans. Lead is a neurotoxin that accumulates both in soft tissues and the bones, damaging the nervous system and causing brain disorders. Excessive lead also causes blood disorders in mammals. Lead poisoning has been documented since ancient Rome, ancient Greece, and ancient China.

In electronics, a lead is an electrical connection consisting of a length of wire or metal pad ( SMD) that comes from a device. Leads are used for physical support, to transfer power, to probe circuits (see multimeter), to transmit information, and sometimes as a heatsink. The tiny leads coming off through-hole components are also often called pins.

Many electrical components such as capacitors, resistors, and inductors have only two leads where some integrated circuits (ICs) can have several hundred leads to more than a thousand for the largest BGA devices. IC pins often either bend under the package body like a letter "J" (J-lead) or come out, down, and form a flat foot for securing to the board (S-lead or gull-lead).

Most kinds of integrated circuit packaging are made by placing the silicon chip on a lead frame, wire bonding the chip to the metal leads of that lead frame, and covering the chip with plastic. The metal leads protruding from the plastic are then either "cut long" and bent to form through-hole pins, or "cut short" and bent to form surface-mount leads. Such lead frames are used for surface mount packages with leads—such as small-outline integrated circuit (SOIC), Quad Flat Package (QFP), etc. -- and for through-hole packages such as dual in-line package (DIP) etc. -- and even for so-called "leadless" or "no-lead" packages—such as quad-flat no-leads package (QFN), etc.

The lead frame (and therefore the pins, if any, formed from that lead frame) are occasionally made from FeNi42, a kind of Invar.

A lead, lead line, lead rope (USA) or head collar rope (UK), is used to lead an animal such as a horse. Usually, it is attached to a halter. The lead may be integral to the halter or, more often, separate. When separate, it is attached to the halter with a heavy clip or snap so that it can be added or removed as needed. A related term, lead shank or lead chain refers to a lead line with a chain attached that is used in a variety of ways to safely control possibly difficult or dangerous horses if they will not respond to a regular lead.

Lead is the axial advance of a helix or screw during one complete turn (360°) The lead for a screw thread is the axial travel for a single revolution.

Pitch is defined as the axial distance between adjacent threads on a helix or screw. In most screws, called "single start" screws, which have a single helical thread along their length, the lead and pitch are equal. They only differ in "multiple start" screws, which have several intertwined threads. In these screws, the lead is equal to the pitch multiplied by the number of "starts".

Lead angle is the angle between the helix and a plane of rotation. It is the complement of the helix angle, and is used for convenience in worms and hobs. It is understood to be at the standard pitch diameter unless otherwise specified.

The lead angle can be expressed as:

$$\mbox{Lead angle} = \arctan \left( \frac {l} {\pi d_m} \right)$$

where

In American literature λ is used to notate the Lead Angle. In European literature, Υ (Greek letter gamma) may be used.

Lead refers to which set of legs, left or right, leads or advances forward to a greater extent when a quadruped animal is cantering, galloping, or leaping. The feet on the leading side touch the ground forward of its partner. On the "left lead", the animal's left legs lead. The choice of lead is of special interest in horse riding.

A lead change refers to an animal, usually a horse, moving in a canter or gallop, changing from one lead to the other. There are two basic forms of lead change: simple and flying. It is very easy to define the correct lead from the incorrect lead. When a horse is executing the correct lead, the inside front and hind legs reach farther forwards than the outside legs.

In a transverse or lateral or united canter and gallop, the hind leg on the same side as the leading foreleg (the lateral hindleg) advances more. In horses this is the norm.

In a rotatory or diagonal or disunited canter and gallop, the hind leg on the opposite side (the diagonal hindleg) advances more. In horses, it is more often than not an undesirable gait form, also known as rotary and round galloping, and as moving disunited, cross-firing, and cross-cantering. In animals such as dogs, deer, and elk, however, this form of the gait is the norm.

Some authorities define the leading leg in the singular form as the last to leave the ground before the one or two periods of suspension within each stride. In these cases, because the canter has only one moment of suspension, the leading leg is considered to be the foreleg. Because in some animals the gallop has two moments of suspension, some authorities recognize a lead in each pair of legs, fore and hind. So when an animal is in a rotatory gait, it is called disunited, due to different leading legs in the front and hind.

A lead is a large fracture within an expanse of sea ice, defining a linear area of open water that can be used for navigation purposes. Leads vary in width from meters to hundreds of meters. As is the case for polynyas (another sea ice feature involving open water), leads allow the direct interaction between the atmosphere and the ocean, and are important for Arctic sea ice ecology. Additionally it has been lately found that ice leads contribute significantly to the amount of mercury deposited onto surface and leaked into the ocean. If the air is cold enough (typically in the winter), the water within a lead quickly refreezes, such that in many cases, leads are partly or entirely covered by a thin layer of new ice.

In curling, the lead is the person who delivers the first two stones of the end for their team. On most teams, where the lead does not act as skip or vice, the lead will sweep for each of his teammates. Because of the free-guard rule, which prevents leads from removing most of an opponents stones, leads are usually proficient at throwing guards and other draws, and throw few takeouts or other power shots. In some regions, such as Eastern Ontario and the Eastern United States, the lead is responsible for determining who has hammer, using random selection, such as flipping a coin. However, in most regions, this is the responsibility of the third.