The Collaborative International Dictionary of English v.0.48:

Abortifacient \A*bor`ti*fa"cient\
   ([.a]*b[^o]r`t[i^]*f[=a]"shent), a. [L. abortus (see Abort,
   v.) + faciens, p. pr. of facere to make.]
   Producing miscarriage. -- n. A drug or an agent that causes
   premature delivery.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Abortive \A*bor"tive\, n.
   1. That which is born or brought forth prematurely; an
      abortion. [Obs.] --Shak.
      [1913 Webster]

   2. A fruitless effort or issue. [Obs.]
      [1913 Webster]

   3. (Med.) A medicine to which is attributed the property of
      causing abortion; -- also called an abortifacient.
      --Dunglison.
      [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

abortifacient
    adj 1: causing abortion
    n 1: a drug (or other chemical agent) that causes abortion [syn:
         abortifacient, aborticide, abortion-inducing drug]