WordNet (r) 3.0 (2006):

behaviour
    n 1: the action or reaction of something (as a machine or
         substance) under specified circumstances; "the behavior of
         small particles can be studied in experiments" [syn:
         behavior, behaviour]
    2: (behavioral attributes) the way a person behaves toward other
       people [syn: demeanor, demeanour, behavior,
       behaviour, conduct, deportment]
    3: (psychology) the aggregate of the responses or reactions or
       movements made by an organism in any situation [syn:
       behavior, behaviour]
    4: manner of acting or controlling yourself [syn: behavior,
       behaviour, conduct, doings]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

BEHAVIOUR. In old English, haviour without the prefix be. It is the manner
of having, holding, or keeping one's self or the carriage of one's self with
respect to propriety, morals, and the requirements of law. Surety to be of -
good behaviour is a larger requirement than surety to keep the peace.
Dalton, c. 122; 4 Burn's J. 355.