Meaning of quod erat demonstrandum in English:

quod erat demonstrandum

Pronunciation /kwɒd ˌɛrat dɛmənˈstrandəm/

exclamation

(also QED)
  • 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’.