The Collaborative International Dictionary of English v.0.48:

Inhibit \In*hib"it\, v. t. [imp. & p. p. Inhibited; p. pr. &
   vb. n. Inhibiting.] [L. inhibitus, p. p. of inhibere; pref.
   in- in + habere to have, hold. See Habit.]
   [1913 Webster]
   1. To check; to hold back; to restrain; to hinder.
      [1913 Webster]

            Their motions also are excited or inhibited . . . by
            the objects without them.             --Bentley.
      [1913 Webster]

   2. To forbid; to prohibit; to interdict.
      [1913 Webster]

            All men were inhibited, by proclamation, at the
            dissolution, so much as to mention a Parliament.
                                                  --Clarendon.
      [1913 Webster]

            Burial may not be inhibited or denied to any one.
                                                  --Ayliffe.
      [1913 Webster]

   3. (Chem., Biochem.) To cause the rate of (a chemical or
      biochemical reaction) to proceed slower, or to halt; as,
      vitamin C inhibits oxidation; penicillins inhibit
      bacterial cell wall synthesis.
      [PJC]

   4. To restrain (a behavior) by a mechanism involving
      conscious or unconscious motivations.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

inhibited \inhibited\ adj.
   1. held back or restrained or prevented; as, in certain
      conditions previously inhibited conditioned reactions can
      reappear; -- of behaviors. Opposite of uninhibited.
      [Narrower terms: pent-up, repressed ; {stifled,
      strangled, suppressed ] Also See: {reserved,
      restrained.
      [WordNet 1.5]

   2. Having a hesitancy or reluctance to exhibit normal
      emotional reactions; -- of people; as, he was too
      inhibited to make friends easily.
      [PJC]

WordNet (r) 3.0 (2006):

inhibited
    adj 1: held back or restrained or prevented; "in certain
           conditions previously inhibited conditioned reactions can
           reappear" [ant: uninhibited]

Moby Thesaurus II by Grady Ward, 1.0:

29 Moby Thesaurus words for "inhibited":
   abashed, arrested, bridled, cold, constrained, controlled, curbed,
   embarrassed, guarded, in check, in leading strings, in remission,
   on leash, passionless, pent-up, repressed, reserved, restrained,
   retarded, reticent, self-conscious, shy, slowed down,
   under control, under discipline, under restraint, undersexed,
   unresponsive, uptight