Douglas Harper's Etymology Dictionary
1760, abbreviation of Latin quod erat demonstrandum "which was to be demonstrated."
Wikipedia
Q.E.D. is an initialism of the Latin phrase , meaning "which is what had to be proved". The phrase is traditionally placed in its abbreviated form at the end of a mathematical proof or philosophical argument when the original proposition has been exactly restated as the conclusion of the demonstration. The abbreviation thus signals the completion of the proof.
Q.E.D. is a 1982 adventure television series set in Edwardian England, starring Sam Waterston as Professor Quentin Everett Deverill. The Professor was a scientific detective in the mold of Sherlock Holmes, and the series had a smattering of what would later be called steampunk. In the show, the lead character was known primarily by his initials, Q.E.D; the reference here is that Q.E.D. usually stands for quod erat demonstrandum, a statement signalling the end of a proof. The show aired on the CBS network in the United States, and by a variety of ITV companies in the United Kingdom.
is a detective manga, created and produced by Motohiro Katou. Sou Touma is a university graduate who encounters a variety of investigative cases after returning to Japan from the US. He works with his friend, Kana Mizuhara, combining his deductive skills with Mizuhara's social gifts.
Q.E.D. has sold over 3 million copies in Japan and has been adapted as a live-action TV series.
Q.E.D. (quod erat demonstrandum, Latin for "that which was to be demonstrated") was the name of a strand of BBC popular science documentary films which aired in the United Kingdom from 1982 to 1999.
Q.E.D. is an album of contemporary classical music by guitarist Terje Rypdal recorded in 1991 and released on the ECM label in 1993.
Q.E.D. is the second widely available studio album by American blues rock musician and computer scientist Jim Allchin. It was released on September 10, 2013 by Sandy Key Music. The title of the album is a reference to quod erat demonstrandum or Q.E.D which is sometimes used to denote the completion of a mathematical proof.