idempotent

Definition

(said of a function) Such that, when performed multiple times on the same subject, it has no further effect on its subject after the first time it is performed.

Etymology

From Latin roots idem (“same”) + potent (“having power”), thus “having the same power”. Coined in 1870 by American mathematician Benjamin Peirce in the context of algebra, later generalized to computer science.

Example Sentences

• "A projection operator is idempotent."
• "An HTTP request using the PUT verb should be idempotent, so that it can be sent to the server any number of times with the same end result."
• "Every finite semigroup has an idempotent element."