Origin and history of tack

[clasp, hook, fastener] late 13c., from Old North French taque "nail, pin, peg" (Old French tache, 12c., "nail, spike, tack; pin brooch"), which is 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"), according to Watkins from Proto-Germanic *tag- (compare tag).

Specifically as "short, sharp-pointed nail with a flat head" by mid-15c.

In sailing by late 14c.; specifically meaning "rope or hooked wire to hold the lower corner of a sail in place" by late 15c. The extended sense of "course of a ship in relation to the position of her sails" is by 1610s. Hence the figurative use for "tactical procedure, course of conduct or mode of action suited to some purpose" (1670s), attested earlier in the verb (1630s). The notion is "temporary change in direction to take advantage of a side-wind."

"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.

"food" in general, but in dialect especially "bad food" or "food for animals," especially among sailors "food of a bread kind," 1830 (implied in hardtack), perhaps a shortening and special use of tackle (n.) in the sense of "gear."

late 14c., transitive, "attach" with a tack, nail, etc., "join or secure by temporary fastening," from tack (n.1). The meaning "attach as a supplement" (with suggestion of hasty or arbitrary proceeding) is from 1680s. Related: Tacked; tacking.

1550s, intransitive, "turn a ship's course toward the wind at an angle" by shifting the tacks of the sails, 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 in order to take advantage of a side-wind. The figurative sense of "change one's course" is from 1630s. Related: Tacked; tacking.