The Collaborative International Dictionary of English v.0.48:

Pinnace \Pin"nace\, n. [F. pinasse; cf. It. pinassa, pinazza,
   Sp. pinaza; all from L. pinus a pine tree, anything made of
   pine, e.g., a ship. Cf. Pine a tree.]
   1. (Naut.)
      (a) A small vessel propelled by sails or oars, formerly
          employed as a tender, or for coast defence; -- called
          originally, spynace or spyne.
      (b) A man-of-war's boat.
          [1913 Webster]

                Whilst our pinnace anchors in the Downs. --Shak.
          [1913 Webster]

   2. A procuress; a pimp. [Obs.] --B. Jonson.
      [1913 Webster]

WordNet (r) 3.0 (2006):

pinnace
    n 1: a boat for communication between ship and shore [syn:
         tender, ship's boat, pinnace, cutter]