behavior

IPA/bɪˈheɪ.vjər/
KK[bɪhˈevjɚ]IPA/bɪˈheɪ.vjɚ/

behavior — noun

  • behaviorsingular
  • behaviorsplural

1. How one acts, especially toward other people or in social situations.

1.nounA2
Definition

How one acts, especially toward other people or in social situations.

Example

Christopher's polite behavior at the dinner table impressed his host's parents.

behavior at [place/event] — specifying context

The teacher praised the class for their excellent behavior during the field trip.

Common collocations
  • good behavior
  • bad behavior
  • rude behavior
  • aggressive behavior
  • polite behavior
  • behavior toward
  • behavior at
  • behavior during
Synonyms
  • conduct

    more formal than 'behavior', often carries a moral judgment — 'professional conduct' sounds more official than 'professional behavior'

  • demeanor

    focuses on the outward appearance and expression of how someone acts, rather than their actions themselves

  • manners

    specifically about politeness and socially expected ways of acting in a culture

Antonyms

Grammar Patterns

adjective + behavior

behavior toward/towards [person]

2. The way a living thing, such as a person, animal, or plant, acts or reacts to wh

2.nounB1
Definition

The way a living thing, such as a person, animal, or plant, acts or reacts to what is happening around it, studied especially in science.

Example

The researchers observed the feeding behavior of wild chimpanzees in the forest of Tanzania.

observed/study + the + __ + behavior + of + [animal]

The cat's fearful behavior before the storm made Eshe wonder if animals sense changing weather.

Common collocations
  • animal behavior
  • human behavior
  • social behavior
  • feeding behavior
  • mating behavior
  • observe behavior
  • study behavior
  • behavior pattern
  • behavior in response to
Synonyms
  • response

    a more general term for any reaction to a stimulus; less tied to personality or character than 'behavior'

  • reaction

    suggests an immediate, often involuntary response rather than an ongoing pattern of behavior

  • action

    the broadest term; any thing a living creature does, without implying a stimulus or pattern

Grammar Patterns

the + behavior + of + [organism]

behavior(s) + in + [situation]

Usage Note

In formal or academic contexts, 'behaviors' (countable plural) is common for listing specific types of actions — for example, 'aggressive behaviors in caged dogs'. In everyday conversation, the uncountable form is preferred: 'The dog's aggressive behavior worried us.'

Common Mistakes

The researcher studied the behavior of plants in different lights.
The researcher studied plant responses to different light levels.
'behavior' for plants is technically correct in botany but sounds unnatural to non-specialists. Use 'response' or 'reaction' for general audiences.

3. The way a machine, substance, or system works when it is in a particular set of

3.nounB2
Definition

The way a machine, substance, or system works when it is in a particular set of circumstances.

Example

The engineer studied the behavior of the steel bridge under strong wind conditions.

behavior of [object] under [condition]

Scientists cannot fully explain the chemical's behavior when mixed with hot water.

Common collocations
  • mechanical behavior
  • chemical behavior
  • thermal behavior
  • elastic behavior
  • material behavior
  • behavior under
  • behavior at
  • behavior in response to
Synonyms
  • performance

    focuses on how well something works rather than how it works; more evaluation-oriented

  • operation

    describes the process of functioning, often of a machine or system over time

  • properties

    refers to the inherent characteristics of a material rather than its active functioning

Grammar Patterns

the + behavior + of + [material/substance/machine]

behavior + under/at/in + [condition]

Usage Note

Most common in engineering, chemistry, physics, and computing. Frequently used with descriptive adjectives such as 'elastic behavior', 'chemical behavior', 'thermal behavior', or 'optical behavior' to name the type of property being studied.

Common Mistakes

The behavior of plastic changes in cold weather.' (too vague for technical writing)
The mechanical behavior of polypropylene changes at temperatures below zero.
In technical contexts, specify what type of behavior (mechanical, chemical, thermal) rather than using 'behavior' alone.

Word family

  • behave
    verbA2
  • behavioral
    adjectiveB1
  • behaviorally
    adverbB2
  • behaviorism
    nounC1
  • behaviorist
    nounC1

Synonym discussion

Sense: noun/1

All three words describe how a person acts, but they emphasize different aspects. 'Conduct' is the most formal of the group and often implies a moral or professional standard — a teacher might discuss 'student conduct' in a disciplinary hearing, whereas 'behavior' sounds more neutral and everyday. 'Demeanor' focuses on the outward look and emotional tone of someone's actions rather than the actions themselves: a person can have a calm demeanor while misbehaving. 'Manners' is narrower, referring specifically to politeness and socially expected routines like saying 'please' and 'thank you.' In practice, a child who uses good manners may still have rude behavior overall, and a person with a stern demeanor may be perfectly kind. For most everyday situations, 'behavior' is the safest, most natural choice for Taiwanese learners.

conduct ↗demeanor ↗manners ↗

Common collocations

Nouns

Adverbs

Phrases

  • code of behavior
  • behavior in the workplace
  • behavior over time
  • range of behaviors

Prepositions

Etymology

Old EnglishMiddle EnglishLatinFrenchEnglish

'Behavior' comes from the verb 'behave' (about 1400s) plus the noun suffix '-ior', a variant of '-or' from Latin. 'Behave' itself formed in Middle English from 'be-' (thoroughly) and 'have', from Old English 'habban' (to have, to hold). The original meaning was 'to contain or restrain oneself', which gradually shifted by the 1500s to mean 'to conduct oneself in a particular way'. The spelling 'behavior' with '-ior' is standard in American English; British English uses 'behaviour' with '-our'.