stadium (n.)youdaoicibaDictYouDict[stadium 词源字典]
late 14c., "a foot race; an ancient measure of length," from Latin stadium "a measure of length; a course for foot-racers" (commonly one-eighth of a Roman mile or a little over 600 English feet; translated in early English Bibles by furlong), from Greek stadion "a measure of length; a race-course, a running track," especially the track at Olympia, which was one stadion in length. The meaning "running track," recorded in English from c. 1600, was extended to mean in modern-day context "large, open oval structure with tiers of seats for viewing sporting events" (1834).

"Originally the distance between successive stations of the shouters and runners employed to estimate distances" [Century Dictionary]. According to Barnhart, the Greek word might literally mean "fixed standard of length" (from stadios "firm, fixed," from PIE root *sta- "to stand"), or it may be from spadion, from span "to draw up, pull," with form influenced by stadios.[stadium etymology, stadium origin, 英语词源]
track (n.)youdaoicibaDictYouDict
late 15c., "footprint, mark left by anything," from Old French trac "track of horses, trace" (mid-15c.), possibly from a Germanic source (compare Middle Low German treck, Dutch trek "drawing, pulling;" see trek). Meaning "lines of rails for drawing trains" is from 1805. Meaning "branch of athletics involving a running track" is recorded from 1905. Meaning "single recorded item" is from 1904, originally in reference to phonograph records. Meaning "mark on skin from repeated drug injection" is first attested 1964.

Track record (1955) is a figurative use from racing, "performance history" of an individual car, runner, horse, etc. (1907, but the phrase was more common in sense "fastest speed recorded at a particular track"). To make tracks "move quickly" is American English colloquial first recorded 1835; to cover (one's) tracks in the figurative sense first attested 1898; to keep track of something is attested from 1883. American English wrong side of the tracks "bad part of town" is by 1901. Track lighting attested from 1970.