a calculus or concretion found in the stomach or intestines of certain animals, esp. ruminants, formerly reputed to be an effective remedy for poison.
a screen or mat covered with a dark material for shielding a camera lens from excess light or glare.
a printed punctuation mark (‽), available only in some typefaces, designed to combine the question mark (?) and the exclamation point (!), indicating a mixture of query and interjection, as after a rhetorical question.
to change the course of a sailing vessel by bringing the head into the wind and then causing it to fall off on the other side: He ordered us to tack at once.
b.
(of a sailing vessel) to change course in this way.
c.
to proceed to windward by a series of courses as close to the wind as the vessel will sail.
16.
to take or follow a zigzag course or route.
17.
to change one's course of action, conduct, ideas, etc.
18.
to equip a horse with tack (usually followed by up): Please tack up quickly.
Idiom
19.
on the wrong tack, under a misapprehension; in error; astray: His line of questioning began on the wrong tack.
Origin: 1300–50; (noun) Middle English tak buckle, clasp, nail (later, tack); cognate with German Zacke prong, Dutch tak twig; (v.) Middle English tacken to attach, derivative of the noun; see tache, attach