The Collaborative International Dictionary of English v.0.48:

Specimen \Spec"i*men\, n. [L., fr. specere to look, to behold.
   See Spy.]
   A part, or small portion, of anything, or one of a number of
   things, intended to exhibit the kind and quality of the
   whole, or of what is not exhibited; a sample; as, a specimen
   of a man's handwriting; a specimen of a person's blood; a
   specimen of painting; aspecimen of one's art.
   [1913 Webster +PJC]

   Syn: Sample; model; pattern.

   Usage: Specimen, Sample. A specimen is a representative
          of the class of things to which it belongs; as, a
          specimen of photography. A sample is a part of the
          thing itself, designed to show the quality of the
          whole; as, a sample of sugar or of broadcloth. A
          cabinet of minerals consists of specimens; if a part
          be broken off from any one of these, it is a sample of
          the mineral to which it belongs. "Several persons have
          exhibited specimens of this art before multitudes of
          beholders." --Addison. "I design this but for a sample
          of what I hope more fully to discuss." --Woodward.
          [1913 Webster]

WordNet (r) 3.0 (2006):

specimen
    n 1: an example regarded as typical of its class
    2: a bit of tissue or blood or urine that is taken for
       diagnostic purposes; "they collected a urine specimen for
       urinalysis"