Idempotent
Etymology
Coined by mathematician Benjamin Peirce in 1870, from Latin "idem," the same, and "potent," having power — literally "same-powered." It first described algebraic operations that repeat without further effect, and later became prized in computing for operations you can retry safely. Flag the coinage.
adjective · /eye-dem-POH-tunt/
Describing an operation that produces the same result no matter how many times it is applied after the first.
What it names
A precise word for actions that are safe to repeat — a design goal in software and a useful property in life, where you want pressing "save" twice, or resending a payment, to do no extra harm.
Example
Make the delete endpoint idempotent, so a user who taps it twice on a flaky connection doesn’t trigger an error.
Related idea
Related to robustness but narrower: robustness is broad tolerance of stress and variation, while idempotence is the specific guarantee that repetition alone changes nothing after the first application.
See also