The Collaborative International Dictionary of English v.0.48:

Non prosequitur \Non" pro*seq"ui*tur\ [L. he does not
   prosecute.] (Law)
   A judgment entered against the plaintiff in a suit where he
   does not appear to prosecute. See Nolle prosequi.
   [1913 Webster]

WordNet (r) 3.0 (2006):

non prosequitur
    n 1: a judgment entered in favor of the defendant when the
         plaintiff has not continued his action (e.g., has not
         appeared in court) [syn: non prosequitur, non pros]