Source : Webster's Revised Unabridged Dictionary (1913)

Preen \Preen\, v. t. [imp. & p. p. {Preened}; p. pr. & vb. n.
   {Preening}.] [See {Preen}, n.; or cf. {Prune}.]
   1. To dress with, or as with, a preen; to trim or dress with
      the beak, as the feathers; -- said of birds. --Derham.

   2. To trim up, as trees. [Prov. Eng.] --Halliwell.