# Definition:Operation/Unary Operation

(Redirected from Definition:Unary Operation)

## Definition

A unary operation is the special case of an operation where the operation has exactly one operand.

Thus, a unary operation on a set $S$ is a mapping whose domain and codomain are both $S$.

## Examples

### Square Root

An example of a unary operation from algebra is $\sqrt{}$ (that is, the square root sign).

### All Mappings are Unary

To a set theorist, all mappings are unary operations.

## Linguistic Note

The word unary is pronounced yoo-nary.

Hence when the indefinite article precedes it, the form is (for example) a unary operation.