The Collaborative International Dictionary of English v.0.48:

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.
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            And tacks the center to the sphere.   --Herbert.
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   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.
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   3. In parliamentary usage, to add (a supplement) to a bill;
      to append; -- often with on or to; as, to tack on a
      non-germane appropriation to a bill. --Macaulay.
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   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.
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   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.
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