The Collaborative International Dictionary of English v.0.48:

Apiece \A*piece"\, adv. [Pref. a- + piece.]
   Each by itself; by the single one; to each; as the share of
   each; as, these melons cost a shilling apiece. "Fined . . . a
   thousand pounds apiece." --Hume.
   [1913 Webster]

WordNet (r) 3.0 (2006):

apiece
    adv 1: to or from every one of two or more (considered
           individually); "they received $10 each" [syn: each, to
           each one, for each one, from each one, apiece]