(countable, uncountable) A small nail with a flat head.
(countable, uncountable) A thumbtack.
(countable, uncountable) A loose seam used to temporarily fasten pieces of cloth.
(countable, uncountable) The lower corner on the leading edge of a sail relative to the direction of the wind.
(countable, uncountable) A course or heading that enables a sailing vessel to head upwind.
(countable, figuratively, uncountable) A direction or course of action, especially a new one; a method or approach to solving a problem.
(countable, uncountable) The maneuver by which a sailing vessel turns its bow through the wind so that the wind changes from one side to the other.
(countable, uncountable) The distance a sailing vessel runs between these maneuvers when working to windward; a board.
(countable, uncountable) A rope used to hold in place the foremost lower corners of the courses when the vessel is close-hauled; also, a rope employed to pull the lower corner of a studding sail to the boom.
(countable, uncountable) Any of the various equipment and accessories worn by horses in the course of their use as domesticated animals.
(countable, uncountable) The stickiness of a compound, related to its cohesive and adhesive properties.
(countable, uncountable) Food generally; fare, especially of the hard bread or breadlike kind.
(countable, uncountable) That which is attached; a supplement; an appendix.
(countable, obsolete, uncountable) Confidence; reliance.

(transitive) To nail (something) with a tack (small nail with a flat head).
To sew/stitch with a tack (loose seam used to temporarily fasten pieces of cloth).
To weld with initial small welds to temporarily fasten in preparation for full welding.
To maneuver a sailing vessel so that its bow turns through the wind, i.e. the wind changes from one side of the vessel to the other.
(intransitive) To sail to windward using a series of alternate tacks across the wind.
To add something as an extra item.
Synonym of tack up (“to prepare a horse for riding by equipping it with a tack”).
(obsolete, slang) To join in wedlock.

tacks

Toon populariteit in de loop van de tijd