The Collaborative International Dictionary of English v.0.48:

Nicknack \Nick"nack`\, n.
   See Knickknack.
   [1913 Webster]

WordNet (r) 3.0 (2006):

nicknack
    n 1: miscellaneous curios [syn: bric-a-brac, knickknack,
         nicknack, knickknackery, whatnot]