circularity

IPA/ˌsɜːkjəˈlærəti/
IPA/ˌsɜːrkjəˈlærəti/

circularity — noun

1. a problem in an argument or explanation in which the conclusion that you want to

1.nounC1
Definition

a problem in an argument or explanation in which the conclusion that you want to prove is already present in the starting point, so no real evidence or new information is introduced

Example

The judge saw a clear circularity in the lawyer's argument — it proved nothing new.

uncountable: circularity in [someone's] argument

Yasmin's essay pointed out that the theory's circularity made it impossible to test.

pattern: [possessive] circularity

Common collocations
  • logical circularity
  • circularity in reasoning
  • circularity in an argument
  • avoid circularity
  • accuse something of circularity
  • clear circularity
Synonyms
  • tautology

    more specific — a statement that is true by definition but says nothing new; circularity is the broader structure of which tautology can be a part

  • vicious circle

    more concrete — refers to a chain of events where solving one problem creates another, rather than a logical flaw in reasoning

  • self-reference

    broader — not necessarily flawed; self-reference can be valid (e.g. 'This sentence is in English.') while circularity is always a defect

Antonyms
  • linear reasoning

    a style of argument that moves step by step towards a conclusion without returning to the starting point

  • empirical support

    evidence drawn from observation or experiment, which is the opposite of the self-contained nature of a circular argument

Usage Note

Frequently used in academic or formal writing about logic, philosophy, and argumentation. The noun is uncountable in ordinary use; in very technical or logic-specific writing the countable form 'a circularity' is sometimes used to refer to one specific instance of the flaw.

Common Mistakes

The argument has many circularities.
The argument contains a circularity that weakens it.
In ordinary writing, treat circularity as uncountable; use a circumlocution like 'a circular argument' instead of forcing a plural.

2. a measure of how completely round something is; how closely an object's shape ma

2.nounB2
Definition

a measure of how completely round something is; how closely an object's shape matches that of a perfect circle

Example

The engineer checked the circularity of each metal ring before using it in the assembly.

pattern: check/test/measure the circularity of [object]

Kenji used a digital gauge to measure the circularity of the ceramic bowl.

Common collocations
  • near-perfect circularity
  • measure/check/test circularity
  • circularity of [object]
  • circularity tolerance
  • high degree of circularity
Synonyms
  • roundness

    less technical and more general; 'roundness' can describe shapes that are not perfectly circular (e.g. an egg), while 'circularity' usually implies an exact circle

  • rotundity

    formal or humorous — more often used for three-dimensional roundness or plumpness, not engineering precision

  • sphericity

    for three-dimensional objects (balls/spheres), not for flat circles

Antonyms
  • distortion

    a deviation from the intended round shape, often used in manufacturing

  • ellipticity

    the quality of being oval rather than circular, used in geometry and astronomy

Usage Note

Common in engineering, manufacturing, and technical drawing. The noun can be used with a precise measurement: 'a circularity of 0.02 mm' means the object deviates from a perfect circle by at most 0.02 millimetres.

Common Mistakes

The table has good circular.
The table has good circularity.
'Circular' is an adjective; use the noun 'circularity' after the verb 'has'.

Word family

Synonym discussion

Sense: noun/1

All four terms describe reasoning that turns back on itself, but they differ in scope and register. Circularity is the broadest term: it covers any argument where the conclusion is secretly assumed in the premise, making the reasoning invalid without requiring outside evidence. Tautology is a narrower, stricter type of circularity — a statement that is true by definition and therefore conveys no new information (e.g. 'All bachelors are unmarried men'). Vicious circle (or vicious cycle) shifts the focus from logic to real-world situations: a problem that creates another problem, which then makes the original problem worse (e.g. poverty leading to poor education leading to poverty). Self-reference is a neutral structural feature — a statement that refers to itself — and is not inherently a flaw: 'This sentence contains five words' is self-referential but perfectly meaningful. In academic writing, circularity is the preferred term for critiquing a theory or argument, while tautology is used for statements that are empty by definition.

circularity ↗tautology ↗vicious circleself-reference

Common collocations

Nouns

  • logical circularity
  • circularity error
  • circularity argument

Phrases

  • a circularity of reasoning
  • a degree of circularity

Prepositions

  • circularity in (an argument, reasoning)
  • circularity of (an object)

Etymology

LatinEnglish

From Latin 'circularis' (round, like a circle) combined with the English suffix '-ity' (forming nouns that mean 'quality or state of'). The geometric sense — describing how round something is — appeared in the 1500s. The logical sense developed in the 1600s, as writers began using the image of a circle to describe arguments that 'go round in a circle' and never reach a real conclusion.