late 14c., "follow (a course); draw a line, make an outline of something," also figurative; "ponder, investigate," from Old French tracier "look for, follow, pursue" (12c., Modern French tracer), from Vulgar Latin *tractiare "delineate, score, trace" (source also of Spanish trazar "to trace, devise, plan out," Italian tracciare "to follow by foot"), a frequentative form from Latin tractus "track, course," literally "a drawing out," from past participle stem of trahere "to pull, draw" (see tract (n.1)).
Meaning "move along, pass over" (a path, etc.) is attested from c. 1400; that of "track down, follow the trail of" is early 15c. Meaning "copy a drawing on a transparent sheet laid over it" is recorded from 1762. Related: Traced; tracing.