trace

n. [ F. trais. pl. of trait. See Trait. ] 1. One of two straps, chains, or ropes of a harness, extending from the collar or breastplate to a whiffletree attached to a vehicle or thing to be drawn; a tug. [ 1913 Webster ]

2. (Mech.) A connecting bar or rod, pivoted at each end to the end of another piece, for transmitting motion, esp. from one plane to another; specif., such a piece in an organ-stop action to transmit motion from the trundle to the lever actuating the stop slider. [ Webster 1913 Suppl. ]

v. i. To walk; to go; to travel. [ Obs. ] [ 1913 Webster ]

Not wont on foot with heavy arms to trace. Spenser. [ 1913 Webster ]

n. [ F. trace. See Trace, v. t. ] 1. A mark left by anything passing; a track; a path; a course; a footprint; a vestige; as, the trace of a carriage or sled; the trace of a deer; a sinuous trace. Milton. [ 1913 Webster ]

2. (Chem. & Min.) A very small quantity of an element or compound in a given substance, especially when so small that the amount is not quantitatively determined in an analysis; -- hence, in stating an analysis, often contracted to tr. [ 1913 Webster ]

3. A mark, impression, or visible appearance of anything left when the thing itself no longer exists; remains; token; vestige. [ 1913 Webster ]

The shady empire shall retain no trace
Of war or blood, but in the sylvan chase. Pope. [ 1913 Webster ]

4. (Descriptive Geom. & Persp.) The intersection of a plane of projection, or an original plane, with a coordinate plane. [ 1913 Webster ]

5. (Fort.) The ground plan of a work or works. [ 1913 Webster ]

Syn.-Vestige; mark; token. See Vestige. [ 1913 Webster ]

a. Capable of being traced. -- Trace"a*ble*ness, n. -- Trace"a/bly, adv. [ 1913 Webster ]

n. One who, or that which, traces. [ 1913 Webster ]

2. A person engaged (esp. in the express or railway service) in tracing, or searching out, missing articles, as packages or freight cars. [ Webster 1913 Suppl. ]

3. An inquiry sent out (esp. in transportation service) for a missing article, as a letter or an express package. [ Webster 1913 Suppl. ]

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. [ PJC ]

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

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. 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. [ PJC ]