What does unary mean?
Unary means involving or consisting of just one element. Its clearest use is in mathematics and computing, where a unary operation acts on one input: negation, for example, changes the sign of a single number and can therefore be represented by a unary minus sign. This contrasts with a binary operation, such as addition, which combines two inputs. More broadly, unary describes something made up of a single part, member, or unit, although this use is less frequent than the technical one. The word is especially associated with formal and specialized writing rather than everyday conversation. Its single-element character makes it useful for describing systems, operations, and structures whose defining feature is that they involve one component. Its history is transparent: it comes from the Latin word for one, the same root that also lies behind unity, unify, and uniform.
adjectiveConsisting of, involving, or operating on a single element, term, or operand. In mathematics and computing, a unary operation takes one input, as distinct from a binary operation, which takes two.
- In mathematics or computing, involving a single operand or input.
- Consisting of one part, member, or unit.
"The unary minus sign changes a positive number into its negative counterpart."
"Negation is a unary operation because it acts on just one value."
"The design was described as unary because all of its elements were arranged along a single axis."
From the same Latin root as unity, unary literally points to something made of one.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of unary
Unary was formed in English from Latin unus, meaning one, together with the suffix -ary. The word developed in the same general semantic direction as related English terms derived from that Latin root: toward unity or oneness rather than multiplicity. Its relatives include unity, unify, uniform, and unilateral, all of which share the Latin element unus.
Related word forms
How unary is actually used
The word is most common in technical contexts, especially mathematics, programming, and logic. It is formal and precise; in ordinary speech, single is usually more natural.