What is "tracer"

Tracer \Tra"cer\, n. One who, or that which, traces.

2. A person engaged (esp. in the express or railway service) in tracing, or searching out, missing articles, as packages or freight cars.

3. An inquiry sent out (esp. in transportation service) for a missing article, as a letter or an express package.

4. (Mil.) a type of ammunition that emits light or smoke as it moves toward its target, providing a visible path of the projectile in flight so that the point of impact may be observed; -- called also tracer ammunition.

5. (Mil.) the chemical substance used in tracer ammunition to cause it to be visible in flight.

6. a chemical substance with properties, such as radioactivity or fluorescence, which make it easily measurable, used to observe the movements of chemically related substances through a biological, physical, or chemical system; -- in biochemistry, also called labeled compounds.

Note: Radioactive tracers are used, for example, to measure the retention or distribution of residues of drugs after administration to an animal, to determine the type and rate of metabolism; also, to measure the rate of motion of molecules in electrophoresis or the leakage of small quantities of material from a container. Small fluorescent tracers may be attached in many cases to macromolecules such as proteins or nucleic acids, allowing the motions of such macromolecules to be easily observed by their acquired fluorescence, without appreciably changing their properties. In biological and biochemial systems the common radioactive isotopes used in tracers are carbon-14, tritium (hydrogen-3), sulfur-35, phosphorus-32, and iodine-131; other isotopes are also used, including non-radioactive isotopes such as carbon-13.

c.1500, "one who tracks or searches," agent noun from verb form of trace (n.1). Meaning "bullet whose course is made visible" is from 1910.

n. 1 (context chemistry English) A chemical used to track the progress or history of a natural process. 2 A round of ammunition for a firearm that contains magnesium or another flammable substance arranged such that it will burn and produce a visible trail when fired in the dark. 3 The act of tracking or investigating something. 4 A person who traces something.

1. n. an investigator who is employed to find missing persons or missing goods

2. an instrument used to make tracings

3. (radiology) any radioactive isotope introduced into the body to study metabolism or other biological processes

4. ammunition whose flight can be observed by a trail of smoke [syn: tracer bullet]

Tracer may refer to:

Tracer is the name of two fictional supervillains published by DC Comics. He first appeared in Justice League Europe #16 (July 1990), and was created by Keith Giffen, Gerard Jones and Bart Sears. Like the rest of the Extremists he is based on a Marvel Comics villain, in his case Victor Creed/Sabretooth archenemey of James Logan Howlett/Wolverine.

Tracer is a fictional character, a supervillain in the Marvel Comics Universe, in which he is an enemy of Spider-Man. His first appearance was in Friendly Neighborhood Spider-Man #1.

Tracer, in comics, may refer to:

• Tracer (DC Comics), two DC Comics supervillains
• Tracer (Marvel Comics), a Marvel Comics supervillain

It may also refer to:

• Tracer Bullet, one of Calvin's alter egos in Calvin and Hobbes

Transition Radiation Array for Cosmic Energetic Radiation (TRACER) is a balloon flown cosmic ray detector built and designed at the University of Chicago. The detector is designed to measure the energy spectra of cosmic ray nuclei with atomic numbers between five and twenty-six ( boron to iron).

Tracer is the public bus system for the city of Tracy, California, USA and the bus system is unique in that since 2002 every April and December the buses are 100% free to all riders.

Tracer is an Australian rock band from Adelaide, South Australia. Tracer has toured Australia and Europe on many occasions and has had success with their album El Pistolero debuting in the top 10 on the BBC Rock album chart. In 2012 Tracer won the 'Best New Band' in the Classic Rock Roll of Honour Awards.

Tracer is the second studio album by American electronic music duo Teengirl Fantasy. It was released on R&S Records and True Panther Sounds on August 21, 2012. It features vocal contributions from Kelela, Panda Bear, Laurel Halo, and Romanthony.

Tracer (Vietnamese: Truy Sát) is a 2016 Vietnamese martial arts action film directed by Cuong Ngo, action directed by Trung Ly and starring Truong Ngoc Anh, Thien Nguyen, Lamou Vissay, Cuong Seven, Maria Tran, Marcus Guilhem, Hieu Nguyen, Thinh Vinh, Hong Que and Quang Huan. This is an original screenplay written by Nguyen Thi Nhu Khanh. It will be released in Vietnam on April 22, 2016 and 5 May 2016 across Australia and New Zealand cinemas.

Tracer is a player character appearing in the 2016 video game Overwatch, a Blizzard Entertainment developed first-person shooter video game and its related media. Although Tracer is from the Overwatch universe, she was introduced in Blizzard's crossover multiplayer online battle arena game, Heroes of the Storm, in an April 2016 update for that game.

The character, who is of English origin, is known by her call sign: Tracer, although her real name is Lena Oxton. In Overwatch, her character design is noted for being one of the fastest in terms of speed, but weakest in terms of health. Tracer has also been noted to be a peppy and energetic character. She makes use of her speed through teleportation and time traveling abilities that are rooted in an in-universe accident that left her unable to maintain a physical form in the present, until another character invented a device allowing her to control her own time.

Tracer is arguably one of the more notable Overwatch characters, despite Blizzard not having an official outright mascot for the game. Although her profile was boosted by having prominent roles in official Overwatch media, the character was given additional media attention through online controversies—one surrounding one of her victory poses, and another surrounding her prominence in fan-produced pornography that Blizzard has made efforts to remove.