behavior

US: /bɪˈheɪvjɚ/ ,(bi hāv′yər)

WordReference Random House Learner's Dictionary of American English © 2025

be•hav•ior /bɪˈheɪvyɚ/   n. [uncountable]

1. the manner of behaving:
   Your behavior today in class was bad.
2. Psychology
   • the activity of a human or animal that can be observed:
     argued that all behavior is a reaction to something outside an individual.
3. the action of any material under given circumstances:
   Describe the behavior of this metal when heated.

Idioms

4. be on one's best behavior, to act or behave as properly as one can:
   The children were on their best behavior.

be•hav•ior•al, adj.: 

the behavioral sciences.

be•hav•ior•al•ly, adv. 

WordReference Random House Unabridged Dictionary of American English © 2025

be•hav•ior  (bi hāv′yər), n. 

1. manner of behaving or acting.
2. Psychology
   • observable activity in a human or animal.
   • the aggregate of responses to internal and external stimuli.
   • a stereotyped, species-specific activity, as a courtship dance or startle reflex.
3. Sociology Often, behaviors. a behavior pattern.
4. the action or reaction of any material under given circumstances:
   the behavior of tin under heat.

Also,[esp. Brit.,] behaviour. 

• Middle French (h)avoir Latin habēre to have); replacing late Middle English behavoure, behaver. See behave, -or¹
• behave + -ior (on model of havior, variant of havor 1375–1425

be•hav′ior•al, adj. 
be•hav′ior•al•ly, adv. 
Synonyms

• 1. demeanor, manners; bearing, carriage.
  Behavior, conduct, deportment, comportment refer to one's actions before or toward others, esp. on a particular occasion.
  Behavior refers to actions usually measured by commonly accepted standards:
  His behavior at the party was childish.
  Conduct refers to actions viewed collectively, esp. as measured by an ideal standard:
  Conduct is judged according to principles of ethics.
  Deportment is behavior related to a code or to an arbitrary standard:
  Deportment is guided by rules of etiquette. The teacher gave Susan a mark of B in deportment.
  Comportment is behavior as viewed from the standpoint of one's management of one's own actions:
  His comportment was marked by a quiet assurance.

WordReference Random House Learner's Dictionary of American English © 2025

be•hav•iour /bɪˈheɪvyɚ/   n. Chiefly Brit.

1. British Terms behavior.

WordReference Random House Unabridged Dictionary of American English © 2025

be•hav•iour  (bi hāv′yər), n. [Chiefly Brit.]

1. British Terms behavior.

Usage

See -or ¹.

Collins Concise English Dictionary © HarperCollins Publishers::

behaviour, behavior / bɪˈheɪvjə/ noun

1. manner of behaving or conducting oneself
2. on one's best behaviour ⇒ behaving with careful good manners
3. the aggregate of all the responses made by an organism in any situation
4. the action, reaction, or functioning of a system, under normal or specified circumstances

Etymology: 15th Century: from behave; influenced in form by Middle English havior, from Old French havoir, from Latin habēre to have

beˈhavioural, beˈhavioral adjective