An initialization subroutine that completes an action only once, even if the routine is called more than once.

Having the same effect as if used only once, even if used multiple times. C header files are usually designed to be idempotent.

adj. Acting exactly once; innocuous if re-applied. In C, usually refers to header files; see questions 10.7 and 11.21.

A matrix is idempotent if A2 = A.

unchanged in value following multiplication by itself; "this matrix is idempotent"

Property of an interaction whose results and side-effects are the same whether it is done one or multiple times. [RFC 2616] Safe interactions are inherently idempotent.

imposition installing a browser interpreter ISWYM

A value is idempotent under a binary operation if the result of applying that operation to the value is the same value.

A class of operations. An operation is idempotent if its results do not affect the results of any operation. For example, a call that returns the time is idempotent.