Source : Webster's Revised Unabridged Dictionary (1913)

Tack \Tack\, v. t. [imp. & p. p. {Tacked}; p. pr. & vb. n.
   {Tacking}.] [Cf. OD. tacken to touch, take, seize, fix, akin
   to E. take. See {Tack} a small nail.]
   1. To fasten or attach. ``In hopes of getting some commendam
      tacked to their sees.'' --Swift.

            And tacks the center to the sphere.   --Herbert.

   2. 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.

   3. In parliamentary usage, to add (a supplement) to a bill;
      to append; -- often with on or to. --Macaulay.

   4. (Naut.) 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.

   Note: In tacking, a vessel is brought to point at first
         directly to windward, and then so that the wind will
         blow against the other side.

Tack \Tack\, n. [From an old or dialectal form of F. tache. See
   {Techy}.]
   1. A stain; a tache. [Obs.]

   2. [Cf. L. tactus.] A peculiar flavor or taint; as, a musty
      tack. [Obs. or Colloq.] --Drayton.

Tack \Tack\, n. [OE. tak, takke, a fastening; akin to D. tak a
   branch, twig, G. zacke a twig, prong, spike, Dan. takke a
   tack, spike; cf. also Sw. tagg prickle, point, Icel. t[=a]g a
   willow twig, Ir. taca a peg, nail, fastening, Gael. tacaid,
   Armor. & Corn. tach; perhaps akin to E. take. Cf. {Attach},
   {Attack}, {Detach}, {Tag} an end, {Zigzag}.]
   1. A small, short, sharp-pointed nail, usually having a
      broad, flat head.

   2. That which is attached; a supplement; an appendix. See
      {Tack}, v. t., 3. --Macaulay.

            Some tacks had been made to money bills in King
            Charles's time.                       --Bp. Burnet.

Tack \Tack\, v. i. (Naut.)
   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.

         Monk, . . . when he wanted his ship to tack to
         larboard, moved the mirth of his crew by calling out,
         ``Wheel to the left.''                   --Macaulay.

Source : WordNet®

tack
     v 1: fasten with tacks; "tack the notice on the board"
     2: turn into the wind; "The sailors decided to tack the boat";
        "The boat tacked" [syn: {wear round}]
     3: make by putting pieces together; "She pieced a quilt"; "He
        tacked together some verses" [syn: {assemble}, {piece}, {put
        together}, {set up}, {tack together}] [ant: {disassemble}]
     4: sew together loosely, with large stitches; "baste a hem"
        [syn: {baste}]
     5: fix to; attach; "append a charm to the necklace" [syn: {append},
         {tag on}, {tack on}, {hang on}]
     6: reverse (a direction, attitude, or course of action) [syn: {interchange},
         {switch}, {alternate}, {flip}, {flip-flop}]

tack
     n 1: the heading or position of a vessel relative to the trim of
          its sails
     2: a short nail with a sharp point and a large head
     3: gear for a horse [syn: {stable gear}, {saddlery}]
     4: (nautical) a line (rope or chain) that regulates the angle
        at which a sail is set in relation to the wind [syn: {sheet},
         {mainsheet}, {weather sheet}, {shroud}]
     5: (nautical) the act of changing tack [syn: {tacking}]
     6: sailing a zigzag course