tight (adj.) Look up tight at Dictionary.com
c. 1400, tyght "dense, close, compact," from Middle English thight, from Old Norse þettr "watertight, close in texture, solid," and also from Old English -þiht (compare second element in meteþiht "stout from eating"), both from Proto-Germanic *thinhta- (cognates: Middle High German dihte "dense, thick," German dicht "dense, tight," Old High German gidigan, German gediegen "genuine, solid, worthy"), from PIE root *tenk- (2) "to become firm, curdle, thicken" (cognates: Irish techt "curdled, coagulated," Lithuanian tankus "close, tight," Persian tang "tight," Sanskrit tanakti "draws together, contracts").

Sense of "drawn, stretched" is from 1570s; meaning "fitting closely" (as of garments) is from 1779; that of "evenly matched" (of a contest, bargain, etc.) is from 1828, American English; that of "drunk" is from 1830. Of persons, "close, intimate, sympathetic" from 1956. From 1670s as an adverb; to sit tight is from 1738; sleep tight as a salutation in sending someone off to bed is by 1871. Related: Tightly; tightness. Tight-assed "unwilling to relax" is attested from 1903. Tight-laced is recorded from 1741 in both the literal and figurative senses. Tight-lipped is first attested 1872.