definition

American  

[def-uh-nish-uhn] / ˌdɛf əˈnɪʃ ən /

noun

definitions plural

1. the act of defining, or of making something definite, distinct, or clear.

   We need a better definition of her responsibilities.

2. the formal statement of the meaning or significance of a word, phrase, idiom, etc., as found in dictionaries. An online dictionary resource, such as Dictionary.com, can give users direct, immediate access to the definitions of a term, allowing them to compare definitions from various dictionaries and stay up to date with an ever-expanding vocabulary.

3. the condition of being definite, distinct, or clearly outlined.

   His biceps have great muscle definition.

4. Optics. sharpness of the image formed by an optical system.

5. Radio and Television. the accuracy of sound or picture reproduction.

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definition British  

/ ˌdɛfɪˈnɪʃən /

noun

1. a formal and concise statement of the meaning of a word, phrase, etc

2. the act of defining a word, phrase, etc

3. specification of the essential properties of something, or of the criteria which uniquely identify it

4. the act of making clear or definite

5. the state or condition of being clearly defined or definite

6. a measure of the clarity of an optical, photographic, or television image as characterized by its sharpness and contrast

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Other Word Forms

Derived Forms

• predefinition
  noun
• redefinition
  noun
• self-definition
  noun
• subdefinition
  noun
• definitional
  adjective
• definitionally
  adverb

Inflected Forms

Nouns

• definitions
  plural

Etymology

Origin of definition

First recorded in 1350–1400; Middle English diffinicioun, from Old French diffinition, from Latin dēfīnītiōn- (stem of dēfīnītiō ), equivalent to dēfīnīt(us) ( see definite) + -iōn- noun suffix ( see -ion)

Explanation

A good definition explains concisely what something means. Dictionaries include definitions, even for the word definition! A definition precisely explains the fundamental state or meaning of something, often given formally as by lexicographers writing a dictionary or legislators writing laws. It can also refer to a sharply detailed image or concept — like how clear the picture is on a high-definition TV or how cut a Calvin Klein model's abs are.

Example Sentences

"Global health, by definition, is transnational, crosses borders, does not concern just one country. Global health problems require global approaches, and no country can go it alone."

From BBC • Jul. 7, 2026

“We wouldn’t have so many books and articles and disputes about this if it weren’t about definition and concept,” Maier said.

From Slate • Jul. 4, 2026

The show still cares about cooking on a budget, but Celenza’s definition of “struggle” has expanded.

From Salon • Jul. 2, 2026

Associations representing nurses and other professions subject to the lower limit challenged the agency’s definition of professional program.

From MarketWatch • Jul. 1, 2026

Indeed, because all facts are by definition true we tend to think all truths are facts.

From "The Invention of Science" by David Wootton

Related Words

• answer
• explanation
• interpretation
• rationale
• solution
• translation