Definition of quod erat demonstrandum in English:

quod erat demonstrandum

(also QED)

exclamation

  • Used to convey that a fact or situation demonstrates the truth of one's theory or claim, especially to mark the conclusion of a formal proof.

Origin

Latin, literally which was to be demonstrated.

Pronunciation:

quod erat demonstrandum

/kwɒd ˌɛrat dɛmənˈstrandʊm/