Source : Webster's Revised Unabridged Dictionary (1913)

Belay \Be*lay"\, v. t. [imp. & p. p. {Belaid}, {Belayed}; p. pr.
   & vb. n. {Belaying}.] [For senses 1 & 2, D. beleggen to
   cover, belay; akin to E. pref. be-, and lay to place: for
   sense 3, OE. beleggen, AS. belecgan. See pref. {Be-}, and
   {Lay} to place.]
   1. To lay on or cover; to adorn. [Obs.]

            Jacket . . . belayed with silver lace. --Spenser.

   2. (Naut.) To make fast, as a rope, by taking several turns
      with it round a pin, cleat, or kevel. --Totten.

   3. To lie in wait for with a view to assault. Hence: to block
      up or obstruct. [Obs.] --Dryden.

   {Belay thee!} Stop.

Source : WordNet®

belay
     n : something to which a mountain climber's rope can be secured
     v 1: turn a rope round an object or person in order to secure it
          or him
     2: fasten a boat to a bitt, pin, or cleat