1. (n.) A stain; a tache.

2. (n.) A peculiar flavor or taint; as, a musty tack.

3. (n.) A small, short, sharp-pointed nail, usually having a broad, flat head.

4. (n.) That which is attached; a supplement; an appendix. See Tack, v. t., 3.

5. (n.) A rope used to hold in place the foremost lower corners of the courses when the vessel is closehauled (see Illust. of Ship); also, a rope employed to pull the lower corner of a studding sail to the boom.

6. (n.) The part of a sail to which the tack is usually fastened; the foremost lower corner of fore-and-aft sails, as of schooners (see Illust. of Sail).

7. (n.) The direction of a vessel in regard to the trim of her sails; as, the starboard tack, or port tack; -- the former when she is closehauled with the wind on her starboard side; hence, the run of a vessel on one tack; also, a change of direction.

8. (n.) A contract by which the use of a thing is set, or let, for hire; a lease.

9. (v. t.) Confidence; reliance.

10. (v. t.) To fasten or attach.

11. (v. t.) Especially, to attach or secure in a slight or hasty manner, as by stitching or nailing; as, to tack together the sheets of a book; to tack one piece of cloth to another; to tack on a board or shingle; to tack one piece of metal to another by drops of solder.

12. (v. t.) In parliamentary usage, to add (a supplement) to a bill; to append; -- often with on or to.

13. (v. t.) To change the direction of (a vessel) when sailing closehauled, by putting the helm alee and shifting the tacks and sails so that she will proceed to windward nearly at right angles to her former course.

14. (v. i.) To change the direction of a vessel by shifting the position of the helm and sails; also (as said of a vessel), to have her direction changed through the shifting of the helm and sails. See Tack, v. t., 4.

MO aberrancy aberration about ship affix algorithm alter alteration ameliorate annex append approach articulate attach attack azimuth back and fill back band backstrap baste batten batten down be changed be converted into be renewed bear away bear off bear to starboard bearing bearing rein beat beat about bellyband bend bias bind bit blinders blinds bolt bottom out box off branch off branching off braze break breeching bridle bring about bring round buckle butt button cant cant round caparison cast cast about cavesson cement change change course change the bearing change the heading checker checkrein cheekpiece chinband chop chop and change cinch circuitousness clasp cleat clip collar combine come about come around come round compass bearing compass direction cordage cording corner couple course crook crownband crupper curb curve declination deflection degenerate depart from departure deteriorate detour deviance deviancy deviate deviation deviousness digress digression direction discursion divagate divagation divaricate divarication diverge divergence diversify diversion dogleg double double a point dovetail drift drifting equipage equipment errantry excursion excursus exorbitation fashion fasten fastening fetch about fittings fix flop form gag swivel gear girth glue go about guise gybe hackamore hairpin halter hames hametugs harness hasp haul around headgear heading headstall heave round heel hinge hip straps hitch hook improve indirection jam jaquima jerk line jibe jibe all standing join joint kit latch lee side line line of action lines lock magnetic bearing manner manner of working martingale means meliorate method methodology miss stays miter mitigate mode mode of operation mode of procedure modulate modus operandi mortise mutate nail noseband obliquity order outfit paste path peg pererration pin ply pole strap practice procedure proceeding process put about put back rabbet rambling reins relative bearing revive ribbons rig rigging rivet ropework roping round a point routine saddle saddlery scarf screw secure sew shaft tug sheer shift shifting shifting course shifting path side check skew skewer slant slew snaffle snap solder staple stick stitch straying style surcingle sweep swerve swerving