The Collaborative International Dictionary of English v.0.48:

Proscription \Pro*scrip"tion\, n. [L. proscriptio: cf. F.
   proscription.]
   1. The act of proscribing; a dooming to death or exile;
      outlawry; specifically, among the ancient Romans, the
      public offer of a reward for the head of a political
      enemy; as, under the triumvirate, many of the best Roman
      citizens fell by proscription.
      [1913 Webster]

            Every victory by either party had been followed by a
            sanguinary proscription.              --Macaulay.
      [1913 Webster]

   2. The state of being proscribed; denunciation; interdiction;
      prohibition. --Macaulay.
      [1913 Webster]

WordNet (r) 3.0 (2006):

proscription
    n 1: a decree that prohibits something [syn: prohibition,
         ban, proscription]
    2: rejection by means of an act of banishing or proscribing
       someone [syn: banishment, proscription]