quod erat demonstrandum

American  

[kwawd e-raht dey-mawn-strahn-doom, kwod er-uht dem-uhn-stran-duhm] / kwɔd ˈɛ rɑt ˌdeɪ mɔnˈstrɑn dʊm, kwɒd ˈɛr ət ˌdɛm ənˈstræn dəm /

Latin.

1. which was to be shown or demonstrated.

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quod erat demonstrandum British  

/ ˈkwɒd ˈɛræt ˌdɛmənˈstrændʊm /

1.  QED.  (at the conclusion of a proof, esp of a theorem in Euclidean geometry) which was to be proved

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quod erat demonstrandum Cultural  

1. A phrase used to signal that a proof has just been completed. From Latin, meaning “that which was to be demonstrated.”

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Example Sentences

He might usefully have concluded his column with the letters we had to put next to solved mathematical equations: QED — quod erat demonstrandum — just to prove his point.

From Washington Post • Nov. 1, 2019

QED: quod erat demonstrandum, Latin for “which was to be demonstrated or proved.”

From "Charles and Emma: The Darwins' Leap of Faith" by Deborah Heiligman

Their death is merely the quod erat demonstrandum of a mathematical and mechanical proposition.

From Impressions of a War Correspondent by Lynch, George

Therefore men were originally fish, quod erat demonstrandum.

From Voltaire's Philosophical Dictionary by Voltaire

Q.E.D., quod erat demonstrandum, which was to be demonstrated.

From The New Gresham Encyclopedia. Vol. 1 Part 1 A to Amide by Various