"horse's harness, etc.," 1924, shortening of tackle (n.) in sense of "equipment." Tack in a non-equestrian sense as a shortening of tackle is recorded in dialect from 1777.
Old English togædere "so as to be present in one place, in a group, in an accumulated mass," from to (see to) + gædere "together" (adv.), apparently a variant of the adverb geador "together," from Proto-Germanic *gaduri- "in a body," from PIE *ghedh- "to unite, join, fit" (see good, and compare gather).
In reference to single things, "so as to be unified or integrated," from c. 1300. Adjective meaning "self-assured, free of emotional difficulties" is first recorded 1966. German cognate zusammen has as second element the Old High German verbal cognate of English same (Old English also had tosamne "together").
"food" in general, but in dialect especially "bad food," and especially among sailors "food of a bread kind," 1833, perhaps a shortening and special use of tackle (n.) in the sense of "gear." But compare tack "taste" (c. 1600), perhaps a variant of tact.
"turn a ship's course toward the wind at an angle," 1550s, from tack (n.1) in the ship-rigging sense (the ropes were used to move the vessel temporarily to one side or another of its general line of course, to take advantage of a side-wind); hence tack (n.) "course of conduct or mode of action suited to some purpose" (1670s), from figurative use of the verb (1630s). Related: Tacked; tacking.
"clasp, hook, fastener," also "a nail" of some kind, c. 1400, from Old North French taque "nail, pin, peg" (Old French tache, 12c., "nail, spike, tack; pin brooch"), probably from a Germanic source (compare Middle Dutch tacke "twig, spike," Frisian tak "a tine, prong, twig, branch," Low German takk "tine, pointed thing," German Zacken "sharp point, tooth, prong"), from Proto-Germanic *tag-. Meaning "small, sharp nail with a flat head" is attested from mid-15c. The meaning "rope to hold the corner of a sail in place" is first recorded late 15c.
late 14c., "to attach" with a nail, etc., from tack (n.1). Meaning "to attach as a supplement" (with suggestion of hasty or arbitrary proceeding) is from 1680s. Related: Tacked; tacking.
children's three-in-a-row game with Xs and Os, so called by 1892, earlier tit-tat-toe (by 1852, in reminiscences of earlier years), also called noughts and crosses (1852), also oughts and crosses. Probably from the sound of the pencil on the slate with which it originally was played by schoolboys. Also the name of a children's counting rhyme played on slate (also originally tit-tat-toe, by 1842), and compare tick-tack (1580s), a form of backgammon, possibly from French trictrac, perhaps imitative of the sound of tiles on the board.