The Collaborative International Dictionary of English v.0.48:

constipated \constipated\ adj.
   having difficult or incomplete or infrequent evacuation of
   the bowels; costive.
   [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Constipate \Con"sti*pate\, v. t. [imp. & p. p. Constipated; p.
   pr. & vb. n. Constipating.] [L. constipatus, p. p. of
   constipare; con- + stipare to crowd together. See Costive.]
   1. To crowd or cram into a narrow compass; to press together
      or condense. [Obs.]
      [1913 Webster]

            Of cold the property is to condense and constipate.
                                                  --Bacon.
      [1913 Webster]

   2. To stop (a channel) by filling it, and preventing passage
      through it; as, to constipate the capillary vessels.
      [1913 Webster]

   3. (Med.) To render costive; to cause constipation in.
      [1913 Webster]

WordNet (r) 3.0 (2006):

constipated
    adj 1: have difficult or incomplete or infrequent evacuation of
           the bowels [ant: regular, unconstipated]

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "constipated":
   blocked, bound, choked, choked up, clogged, clogged up, congested,
   costive, foul, fouled, full, infarcted, jammed, obstipated,
   obstructed, packed, plugged, plugged up, stopped, stopped up,
   stuffed, stuffed up