tack (n.1) Look up tack at Dictionary.com
"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.
tack (v.1) Look up tack at Dictionary.com
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.
tack (n.2) Look up tack at Dictionary.com
"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.
tack (n.3) Look up tack at Dictionary.com
"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.
tack (v.2) Look up tack at Dictionary.com
"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.