The Collaborative International Dictionary of English v.0.48:

Inhibition \In`hi*bi"tion\, n. [L. inhibitio: cf. F.
   inhibition.]
   [1913 Webster]
   1. The act of inhibiting, or the state of being inhibited;
      restraint; prohibition; embargo.
      [1913 Webster]

   2. (Physiol.) A stopping or checking of an already present
      action; a restraining of the function of an organ, or an
      agent, as a digestive fluid or enzyme, etc.; as, the
      inhibition of the respiratory center by the pneumogastric
      nerve; the inhibition of reflexes, etc.
      [1913 Webster]

   3. (Law) A writ from a higher court forbidding an inferior
      judge from further proceedings in a cause before; esp., a
      writ issuing from a higher ecclesiastical court to an
      inferior one, on appeal. --Cowell.
      [1913 Webster]

   4. (Chem., Biochem.) The reduction in rate or stopping of a
      chemical or biochemical reaction, due to interaction with
      a chemical agent.
      [PJC]

WordNet (r) 3.0 (2006):

inhibition
    n 1: (psychology) the conscious exclusion of unacceptable
         thoughts or desires [syn: inhibition, suppression]
    2: the quality of being inhibited
    3: (physiology) the process whereby nerves can retard or prevent
       the functioning of an organ or part; "the inhibition of the
       heart by the vagus nerve"
    4: the action of prohibiting or inhibiting or forbidding (or an
       instance thereof); "they were restrained by a prohibition in
       their charter"; "a medical inhibition of alcoholic
       beverages"; "he ignored his parents' forbiddance" [syn:
       prohibition, inhibition, forbiddance]