The Collaborative International Dictionary of English v.0.48:

Miscarriage \Mis*car"riage\, n.
   1. Unfortunate event or issue of an undertaking; failure to
      attain a proper or desired result or reach a destination;
      as, a serious miscarriage of justice.
      [1913 Webster]

            When a counselor, to save himself,
            Would lay miscarriages upon his prince. --Dryden.
      [1913 Webster]

   2. Ill conduct; evil or improper behavior; as, the failings
      and miscarriages of the righteous. --Rogers.
      [1913 Webster]

   3. The act of bringing forth a child before the time it is
      viable; a premature birth, resulting in death of the
      fetus; spontaneous abortion.
      [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

miscarriage
    n 1: failure of a plan [syn: miscarriage, abortion]
    2: a natural loss of the products of conception [syn:
       spontaneous abortion, miscarriage, stillbirth] [ant:
       live birth]