Etymology Dictionary

TACK,  a small nail, a fastening; to fasten.  (C.)   M. E. takke.   'Takke, or botun, Fibula,' Prompt. Parv.; where we also find:  'Takkyn, or festyn to-gedur, or some-what sowyn to-gedur.'   The sb. is spelt tak, Legends of Holy Rood, ed. Morris, p. 145, l. 419.   Of Celtic origin.—Irish taca, a peg, pin, nail, fastening; Gael. tacaid, a tack, peg, stab; Breton tach, a nail, tacha, to fasten with a nail.   An initial s appears to have been lost, which appears in Irish stang, a peg, pin, Gael. staing, a peg, clock-pin, allied to E. stake.   From ✔STAG, to strike, to touch, take hold of; Fick, i. 823.   See Stake, Take, and Attach.   2. The nautical use of tack is from the same source.   'In nautical language a tack is the rope which draws forward the lower corner of a square sail, and fastens it to the windward side of the ship in sailing transversely to the wind, the ship being on the starboard or larboard tack according as it presents its right or left side to the wind; the ship is said to tack when it turns towards the wind, and changes the tack on which it is sailing;' Wedgwood.   Cf. to tack, to sew slightly, fasten slightly.   Der. tache, q.v.; and see tack-le.   Also tack-et, a small nail (Levins).