Operator acting on one operand.

Operation involving only one operand.

In mathematics, a unary function is a function that takes one argument.

The unary numeral system is the simplest numeral system to represent natural numbers:.

Unary coding, or the unary numeral system and also sometimes called thermometer code, is an entropy encoding that represents a natural number, n, with a code of length n + 1 (or n ), usually n ones followed by a zero (if natural number is understood as non-negative integer) or with n − 1 ones followed by a zero (if natural number is understood as strictly positive integer).