The Collaborative International Dictionary of English v.0.48:

Luff \Luff\ (l[u^]f), n. [OE. lof, prob. a sort of timber by
   which the course of a ship was directed, perh. a sort of
   paddle; cf. D. loef luff, loeven to luff. The word is perh.
   akin to E. glove. Cf. Aloof.] (Naut.)
      (a) The side of a ship toward the wind.
      (b) The act of sailing a ship close to the wind.
      (c) The roundest part of a ship's bow.
      (d) The forward or weather leech of a sail, especially of
          the jib, spanker, and other fore-and-aft sails.
          [1913 Webster]

   Luff tackle, a purchase composed of a double and single
      block and fall, used for various purposes. --Totten.

   Luff upon luff, a luff tackle attached to the fall of
      another luff tackle. --R. H. Dana, Jr.
      [1913 Webster]