The Collaborative International Dictionary of English v.0.48:

Knickknack \Knick"knack`\, n. [See Knack.]
   A trifle or toy; a bawble; a gewgaw; a tchotchke.
   [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

knickknack
    n 1: a small inexpensive mass-produced article [syn:
         knickknack, novelty]
    2: miscellaneous curios [syn: bric-a-brac, knickknack,
       nicknack, knickknackery, whatnot]