Source : Webster's Revised Unabridged Dictionary (1913)

Compost \Com"post\, v. t.
   1. To manure with compost.

   2. To mingle, as different fertilizing substances, in a mass
      where they will decompose and form into a compost.

Compost \Com"post\ (?; 277), n.[OF. compost, fr. L. compositus,
   p. p. See {Composite}.]
   1. A mixture; a compound. [R.]

            A sad compost of more bitter than sweet. --Hammond.

   2. (Agric.) A mixture for fertilizing land; esp., a
      composition of various substances (as muck, mold, lime,
      and stable manure) thoroughly mingled and decomposed, as
      in a compost heap.

            And do not spread the compost on the weeds To make
            them ranker.                          --Shak.

Source : WordNet®

compost
     n : a mixture of decaying vegetation and manure; used as a
         fertilizer

compost
     v : convert to compost; "compost organic debris"