What is "null"

Null \Null\, a. [L. nullus not any, none; ne not + ullus any, a dim. of unus one; cf. F. nul. See No, and One, and cf. None.]

1. Of no legal or binding force or validity; of no efficacy; invalid; void; nugatory; useless.

   Faultily faultless, icily regular, splendidly null, Dead perfection; no more.
   --Tennyson.

2. Having a value of zero; as, of null utility.

3. (Math.) Empty; having no members; as, the null set.

4. (Computers) Unassigned or meaningless; -- a special value given to variables, especially pointers or logical variables, indicating that it is meaningless and cannot be used in computation; as, an uninitialized pointer in "C" is given a null value. The actual value that is stored in memory to indicate the null condition may vary with the computer language used.

Null \Null\, n.

1. Something that has no force or meaning.

2. That which has no value; a cipher; zero.
   --Bacon.

   Null method (Physics.), a zero method. See under Zero.

Null \Null\, v. t. [From null, a., or perh. abbrev. from annul.] To annul. [Obs.]
--Milton.

Null \Null\, n. [Etymol. uncertain.] One of the beads in nulled work.

"void of legal force," 1560s, from Middle French nul, from Latin nullus "not any, none," from ne- "not, no" (see un-) + illus "any," diminutive of unus "one" (see one).

1. 1 Having no validity, "null and void" 2 insignificant 3 absent or non-existent 4 (context mathematics English) of the null set 5 (context mathematics English) of or comprising a value of precisely zero 6 (context genetics of a mutation English) causing a complete loss of gene function, amorphic. n. 1 A non-existent or empty value or set of values. 2 zero quantity of expression; nothing. 3 Something that has no force or meaning. 4 (context computing English) the ASCII or Unicode character ((lang und sc=Latinx ␀)), represented by a zero value, that indicates no character and is sometimes used as a string terminator. 5 (context computing English) the attribute of an entity that has no valid value. 6 One of the beads in nulled work. 7 (context statistics English) null hypothesis v

2. (context transitive English) to nullify; to annul

adj. lacking any legal or binding force; "null and void" [syn: void]

n. a quantity of no importance; "it looked like nothing I had ever seen before"; "reduced to nil all the work we had done"; "we racked up a pathetic goose egg"; "it was all for naught"; "I didn't hear zilch about it" [syn: nothing, nil, nix, nada, aught, cipher, cypher, goose egg, naught, zero, zilch, zip]

Null may refer to:

In physics a null is a point in a field where the field quantity is zero as the result of two or more opposing quantities completely cancelling each other. The field may be scalar, vector or tensor in nature. Common situations where nulls arise are in the polar patterns of microphones and antennae, and nulls caused by reflections of waves.

Null, also called Null the Living Darkness, is a fictional character appearing in American comic books published by Marvel Comics. Null is a demon and enemy of the Defenders and the Squadron Supreme.

Null is the first EP by the American post-metal band Intronaut. It was released in 2006 on Goodfellow Records.

Null is a Foetus EP released in 1995 by Big Cat in the UK. Null acts as a De facto single for "Verklemmt," released on Gash. Promotional copies of Null were distributed by Sony/Columbia in the US, but the EP had no official US release. Null was later rereleased as half of the Null/Void double-CDEP set.

Null is a special marker used in Structured Query Language (SQL) to indicate that a data value does not exist in the database. Introduced by the creator of the relational database model, E. F. Codd, SQL Null serves to fulfill the requirement that all true relational database management systems (RDBMS) support a representation of "missing information and inapplicable information". Codd also introduced the use of the lowercase Greek omega (ω) symbol to represent Null in database theory. NULL is also an SQL reserved keyword used to identify the Null special marker.

This should not be confused with a value of 0. A null value indicates a lack of a value - a lack of a value is not the same thing as a value of zero in the same way that a lack of an answer is not the same thing as an answer of "no". For example, consider the question "How many books does Juan own?" The answer may be "zero" (we know that he owns none) or "null" (we do not know how many he owns, or doesn't own). In a database table, the column reporting this answer would start out with no value (marked by Null), and it would not be updated with the value "zero" until we have ascertained that Juan owns no books.

SQL null is a state (unknown) and not a value. This usage is quite different from most programming languages, where null means not assigned to a particular instance.

In mathematics, the word null (from meaning "zero", which is from meaning "none") means of or related to having zero members in a set or a value of zero. Sometimes the symbol ∅ is used to distinguish "null" from 0. ℵ is sometimes called Aleph null.

In a normed vector space the null vector is the zero vector; in a seminormed vector space such as Minkowski space, null vectors are, in general, non-zero. In set theory, the null set is the set with zero elements; and in measure theory, a null set is a set with zero measure.

A null space of a mapping is the part of the domain that is mapped into the null element of the image (the inverse image of the null element).

In statistics, a null hypothesis is a proposition presumed true unless statistical evidence indicates otherwise.

In radio electronics, a null is an area or vector in an antenna's radiation pattern where the signal cancels out almost entirely.

This can be an advantage, as nulls in the horizontal plane can be used to protect other transmitters from interference. If not carefully planned however, nulls can unintentionally prevent reception of a signal. Null fill in the vertical plane is used to prevent this.

Also, some directional antennas have very narrow, sharp nulls. These antennas when used for direction finding are aimed away from the signal of interest until the antenna's null is pointed at the signal, and the signal cannot be detected.