The Collaborative International Dictionary of English v.0.48:

Peppercorn \Pep"per*corn`\, n.
   1. A dried berry of the black pepper (Piper nigrum).
      [1913 Webster]

   2. Anything insignificant; a particle.
      [1913 Webster]

WordNet (r) 3.0 (2006):

peppercorn
    n 1: pungent seasoning from the berry of the common pepper plant
         of East India; use whole or ground [syn: pepper,
         peppercorn]