behavior

noun

be·​hav·​ior bi-ˈhā-vyər 

bē-

1

: the way in which someone conducts oneself or behaves (see behave sense 1)

We were grateful for the gracious behavior of our hostess.

The children were rewarded for good behavior.

Be on your best behavior.

also : an instance of such behavior

unacceptable social behaviors

2

a

: the manner of conducting (see conduct entry 1 sense 2) oneself

criminal behavior

normal adolescent behavior

b

: anything that an organism does involving action and response to stimulation

c

: the response of an individual, group, or species to its environment

They are studying the behavior of elephants in the wild.

3

: the way in which something functions or operates

They tested the behavior of various metals under heat and pressure.

Synonyms of behavior

• actions
• demeanor
• attitude

Examples of behavior in a Sentence

I'm surprised by her bad behavior toward her friends.

Students will be rewarded for good behavior.

scientists studying the behavior of elephants

An acceptable social behavior in one country may be unacceptable in another country.

Doctors are trying to educate people about behaviors that can put them at increased risk for skin cancer.

The experiment tested the behavior of various metals under heat and pressure.

Recent Examples on the Web

Leaping around in time, Gilroy draws us into Alex’s world with an effervescent wink at the badness of his behavior. — Owen Gleiberman, Variety, 3 Oct. 2026

That behavior resembles a liquid crystal, where molecules can move freely but still maintain directional alignment. — Aamir Khollam, Interesting Engineering, 3 Oct. 2026

People with eating disorders may exhibit compulsive behaviors around both exercise and eating, including working out for multiple hours every day and carefully calculating every aspect of their diet. — Melissa Rudy, FOXNews.com, 2 Oct. 2026

First our forebears began to imitate peers learned behaviors, creating group norms that supported coordinated work. — Michael Morris, Fortune, 2 Oct. 2026

Word History

Etymology

alteration of Middle English behavour, from behaven "to behave" + -our -or entry 2

First Known Use

15th century, in the meaning defined at sense 1

Phrases Containing behavior

• behavior modification
• behavior therapy
• cognitive behavior therapy
• for good behavior
• on one's best behavior
• on their best behavior

Rhymes for behavior

• behaviour
• havior
• savior
• saviour
• misbehavior
• misbehaviour

Kids Definition

behavior

noun

be·​hav·​ior bi-ˈhā-vyər 

1

: the way in which one conducts oneself

2

: the way in which something (as a machine) behaves

3

: anything that a living being does that involves action and response to stimulation

behavioral

-vyə-rəl 

adjective

Medical Definition

behavior

noun

be·​hav·​ior

variants or chiefly British behaviour

bi-ˈhā-vyər 

1

: the manner of conducting oneself

2

a

: anything that an organism does involving action and response to stimulation

b

: the response of an individual, group, or species to its environment

behavioral adjective

or chiefly British behavioural

-vyə-rəl 

behaviorally adverb

or chiefly British behaviourally

-rə-lē