The Collaborative International Dictionary of English v.0.48:

Neologism \Ne*ol"o*gism\, n. [Cf. F. n['e]ologisme.]
   1. The introduction of new words, or the use of old words in
      a new sense. --Mrs. Browning.
      [1913 Webster]

   2. A new word, phrase, or expression.
      [1913 Webster]

   3. A new doctrine; specifically, rationalism.
      [1913 Webster]

WordNet (r) 3.0 (2006):

neologism
    n 1: a newly invented word or phrase [syn: neologism,
         neology, coinage]
    2: the act of inventing a word or phrase [syn: neologism,
       neology, coinage]