The Collaborative International Dictionary of English v.0.48:

Coerce \Co*erce"\, v. t. [imp. & p. p. Coerced; p. pr. & vb.
   n. Coercing.] [L. co["e]rcere; co- + arcere to shut up, to
   press together. See Ark.]
   1. To restrain by force, especially by law or authority; to
      repress; to curb. --Burke.
      [1913 Webster]

            Punishments are manifold, that they may coerce this
            profligate sort.                      --Ayliffe.
      [1913 Webster]

   2. To compel or constrain to any action; as, to coerce a man
      to vote for a certain candidate.
      [1913 Webster]

   3. To compel or enforce; as, to coerce obedience.

   Syn: To Coerce, Compel.

   Usage: To compel denotes to urge on by force which cannot be
          resisted. The term aplies equally to physical and
          moral force; as, compelled by hunger; compelled
          adverse circumstances; compelled by parental
          affection. Coerce had at first only the negative sense
          of checking or restraining by force; as, to coerce a
          bad man by punishments or a prisoner with fetters. It
          has now gained a positive sense., viz., that of
          driving a person into the performance of some act
          which is required of him by another; as, to coerce a
          man to sign a contract; to coerce obedience. In this
          sense (which is now the prevailing one), coerce
          differs but little from compel, and yet there is a
          distinction between them. Coercion is usually
          acomplished by indirect means, as threats and
          intimidation, physical force being more rarely
          employed in coercing.
          [1913 Webster]

WordNet (r) 3.0 (2006):

coerce
    v 1: to cause to do through pressure or necessity, by physical,
         moral or intellectual means :"She forced him to take a job
         in the city"; "He squeezed her for information" [syn:
         coerce, hale, squeeze, pressure, force]