The Collaborative International Dictionary of English v.0.48:

Imprison \Im*pris"on\, v. t. [imp. & p. p. Imprisoned; p. pr.
   & vb. n. Imprisoning.] [OE. enprisonen, OF. enprisoner, F.
   emprisonner; pref. en- (L. in) + F. & OF. prison. See
   Prison.]
   1. To put in prison or jail; To arrest and detain in custody;
      to confine.
      [1913 Webster]

            He imprisoned was in chains remediless. --Spenser.
      [1913 Webster]

   2. To limit, restrain, or confine in any way.
      [1913 Webster]

            Try to imprison the resistless wind.  --Dryden.

   Syn: To incarcerate; confine; immure.
        [1913 Webster]

WordNet (r) 3.0 (2006):

imprison
    v 1: lock up or confine, in or as in a jail; "The suspects were
         imprisoned without trial"; "the murderer was incarcerated
         for the rest of his life" [syn: imprison, incarcerate,
         lag, immure, put behind bars, jail, jug, gaol,
         put away, remand]
    2: confine as if in a prison; "His daughters are virtually
       imprisoned in their own house; he does not let them go out
       without a chaperone"