What is "christmas tree"

Christmas \Christ"mas\, n. [Christ + mass.] An annual church festival (December 25) and in some States a legal holiday, in memory of the birth of Christ, often celebrated by a particular church service, and also by special gifts, greetings, and hospitality. Christmas box.

1. A box in which presents are deposited at Christmas.

2. A present or small gratuity given to young people and servants at Christmas; a Christmas gift.

   Christmas carol, a carol sung at, or suitable for, Christmas.

   Christmas day. Same as Christmas.

   Christmas eve, the evening before Christmas.

   Christmas fern (Bot.), an evergreen North American fern ( Aspidium acrostichoides), which is much used for decoration in winter.

   Christmas flower, Christmas rose, the black hellebore, a poisonous plant of the buttercup family, which in Southern Europe often produces beautiful roselike flowers midwinter.

   Christmas tree, a small evergreen tree, set up indoors, to be decorated with bonbons, presents, etc., and illuminated on Christmas eve.

A Christmas tree is a decorated tree, usually an evergreen conifer such as spruce, pine, or fir or an artificial tree of similar appearance, associated with the celebration of Christmas. The modern Christmas tree was developed in early modern Germany (where it is today called Weihnachtsbaum or Christbaum) with predecessors that can be traced to the 16th and possibly 15th century, in which devout Christians brought decorated trees into their homes. It acquired popularity beyond Germany during the second half of the 19th century, at first among the upper classes.

The tree was traditionally decorated with edibles such as apples, nuts, or other foods. In the 18th century, it began to be illuminated by candles which were ultimately replaced by Christmas lights after the advent of electrification. Today, there is a wide variety of traditional ornaments, such as garland, tinsel, and candy canes. An angel or star might be placed at the top of the tree to represent the archangel Gabriel or the Star of Bethlehem from the Nativity.

The Christmas tree has also been known as the " Yule-tree", especially in discussions of its folkloric origins.

In petroleum and natural gas extraction, a Christmas tree, or "tree" (not " wellhead" as sometimes incorrectly referred to), is an assembly of valves, spools, and fittings used for an oil well, gas well, water injection well, water disposal well, gas injection well, condensate well and other types of wells. It was named for its crude resemblance to a decorated tree.

A Christmas tree is a festive decoration. It may also refer to:

• Christmas tree (aviation), a term for alert aprons of the United States Air Force during the Cold War
• "Christmas Tree" (Lady Gaga song), a 2008 single by Lady Gaga and Space Cowboy
• Christmas tree (oil well), an assembly of valves used in oil and gas extraction
• The Christmas Tree (1969 film), French film, also known as L'Arbre de Noël
• The Christmas Tree (1996 film), a 1996 TV movie starring Julie Harris and Andrew McCarthy
• The Christmas Tree (novel), a 1981 novel by Irish author Jennifer Johnston
• Christmas tree bill, a political term referring to a bill in the U.S. Congress that attracts many, often unrelated, floor amendments
• The Christmas Tree Cluster, a distinctive star cluster of the astronomical object NGC 2264 in Monoceros constellation
• 'Christmas Tree' formation, a pattern of positions in football
• Christmas Tree Lane, a boulevard in Altadena, California
• Christmas tree packet, a unit of data used in information technology
• Metrosideros excelsa, the pōhutukawa, a New Zealand plant also known as the Christmas tree
• Nuytsia floribunda, a West Australian plant of the genus Nuytsia, also known as the Christmas tree
• Spirobranchus giganteus, a small, tube-building polychaete worm commonly known as the "Christmas tree worm"
• O Christmas Tree, the English version of the song O Tannenbaum
• Christmas tree (drag racing), the series of lights used to start drag races.

A "Christmas tree" was a type of alert area constructed by the United States Air Force for the Strategic Air Command ( SAC) during the Cold War. Oftentimes, bombers or tanker aircraft were stationed next to a readiness crew building (RCB), also known as " mole hole" facilities. The alert apron, also known as an alert ramp, received the name "Christmas tree" because it basically resembled a tree of the same name.

"Christmas Tree" is a song by American singer Lady Gaga. It was released on December 16, 2008 for digital download. It was written and produced by Gaga, Martin Kierszenbaum, and Space Cowboy, who also provides guest vocals. Musically, "Christmas Tree" is a Christmas song with dance-pop and synthpop influences. It samples the classic Christmas song " Deck the Halls", as well as briefly using the lyrics "Rum pum pum pum" from the Christmas song " The Little Drummer Boy" in its intro. Lyrically, the song uses sexual innuendos.

The song received mixed reviews from music critics, with some commending its creativity and individuality from other Christmas songs and others criticizing its sexual innuendos and deeming it "not for the family". Due to strong digital sells, it reached number 79 on the Canadian Hot 100 in January 2009. It also reached number 18 on the Japanese RIAJ Digital Track Chart and number 23 on the Billboard Holiday/Seasonal Digital Songs chart in late 2010. In December 2009, it was available for free download on Amazon as a part of their "25 Days of Free" promotion. It has been included in several Christmas compilation albums, including Now That's What I Call Christmas! 4.

Modern drag races are started electronically by a system known as a Christmas tree. A common Christmas tree consists of a column of seven lights for each driver or lane, as well as a set of light beams across the track itself. Each side of the column of lights is the same; from the top down, there is one blue LED light set arranged in a circle with a white line through the center, then three amber bulbs, then a green bulb and a red bulb. The light beams are arranged with one set on the starting line, and another set 7 inches behind it.

When drivers are preparing to race, they first cross the beams 7 inches behind the starting line. Crossing this beam activates the top half of the circle. Once pre-staged, drivers roll up 7 inches and cross the second beam on the finish line, bottom half of the circle, including the crossing line. Once both drivers have crossed the staged sensor, an official starter or automatic starting system will activate the next lighting sequence.

After this point, the lighting sequence will be different based on the type of tree and start that a race is using. The "Standard" tree will light up each large amber light consecutively with a .500 second delay in between them, then followed by the green light after another .500 second delay. A "Professional" tree will light up all of the large amber lights simultaneously, and then after a .400 second delay, light up the green light. Some classes will use a hybrid tree, known as a .500 Professional tree, where the delay is .500 seconds instead of the .400 seconds used in a standard Professional tree. On the activation of the green light from either style of tree, the drivers are supposed to start the race. Leaving the "Staged" line before the green light activates will instantly stop the count down and result in a lighting of the red light and a provisional disqualification of the offending driver in heads-up starts only. In a Professional Tree or a Standard Tree with a heads-up start, if both drivers leave before the green light activates, only the first to leave will be charged with a provisional disqualification. In a Standard Tree with staggered start times, a green light will be shown to the first driver, regardless if he jumped or not, and once the second driver takes the start, if one driver jumped the start, then that driver's lane will display the red light. If both drivers jump, only the driver whose infraction was worse will be shown the red light, as if it was a heads-up start. If the driver that did not active a red light in his lane commits a further foul during the run (crossing a lane boundary or hitting the barrier), and the driver who commits a red-light foul does not cross a boundary line, the red light violation is overturned and the driver who crosses the boundary line is disqualified, with the driver who committed the red-light foul winning the round.