Q.E.D.

== English == === Etymology === From Late Latin QED, from Latin quod erat demonstrandum. === Pronunciation === (Received Pronunciation) IPA(key): /ˌkjuːiːˈdiː/ (General American) IPA(key): /ˌkjuˌiˈdi/ === Phrase === Q.E.D. (mathematics, dated) Initialism of quod erat demonstrandum (“what was to be proved; what was to be demonstrated”): placed at the end of a mathematical proof to show that the theorem under discussion is proved. (by extension) Used to indicate that an argument or proposition is proved by the existence of some fact or scenario. ==== Usage notes ==== When used to end a mathematical proof, QED is somewhat dated or traditional; modern textbooks often use the graphical symbol ∎ (the halmos or tombstone) instead. Other languages generally use a vernacular abbreviation, such as French CQFD (“ce qu'il fallait démontrer”) or Portuguese C.Q.D. (“como queríamos demonstrar”). ==== Alternative forms ==== QED, Q. E. D., q. e. d., q.e.d. ==== Related terms ==== QEF ==== Translations ==== === Noun === Q.E.D. (plural Q.E.D.s) A certain fact or scenario that proves an argument or proposition; a justification. ==== Alternative forms ==== QED ==== Translations ==== === References === === Further reading === Q.E.D. on Wikipedia.Wikipedia === Anagrams === DEQ