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]

Moby Thesaurus II by Grady Ward, 1.0:

41 Moby Thesaurus words for "miscarriage":
   abortion, abortive attempt, breakdown, clerical error, collapse,
   corrigendum, defeat, dud, erratum, error, failing, failure, fault,
   faute, frustration, human error, merry chase, misapprehension,
   miscalculation, miscarrying, misconception, miscount, misdeal,
   misfire, misidentification, misjudgment, mismanagement, misplay,
   misprint, misquotation, misreport, miss, misstatement, mistake,
   misunderstanding, misuse, typo, typographical error, vain attempt,
   wet squib, wild-goose chase



Bouvier's Law Dictionary, Revised 6th Ed (1856):

MISCARRIAGE, med. jurisp. By this word is technically understood the
expulsion of the ovum or embryo from the uterus within the first six weeks
after conception; between that time and before the expiration of the sixth
month, when the child may possibly live, it is termed abortion. When the
delivery takes place soon after the sixth month, it is denominated premature
labor. But the criminal act of destroying the foetus at any time before
birth, is termed in law, procuring miscarriage. Chit. Med. Jur. 410; 2
Dunglison's Human Physiology, 364. Vide Abortion; Foetus.



Bouvier's Law Dictionary, Revised 6th Ed (1856):

MISCARRIAGE, contracts, torts. By the English statute of frauds, 29, C.
II., c. 3, s. 4, it is enacted that "no action shall be brought to charge
the defendant upon any special promise to answer for the debt, default, or
miscarriage of another person, unless the agreement," &c. "shall be in
writing," &c. The word miscarriage, in this statute comprehends that species
of wrongful act, for the consequences of which the law would make the party
civilly responsible. The wrongful riding the horse of another, without his
leave or license, and thereby causing his death, is clearly an act for which
the party is responsible in damages, and therefore, falls within the meaning
of the word miscarriage. 2 Barn. & Ald. 516; Burge on Sur. 21.