QED

• Q.E.D. / Q. E. D.
• (quod erat demonstrandum): q.e.d.

• IPA^(key): /ˌkjuː ˌiː ˈdiː/

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QED

1. Initialism of quod erat demonstrandum. (Latin quod erat demonstrandum for what had to be proved or what was to be demonstrated); placed at the end of a mathematical proof to show that the theorem under discussion is proved.
   • 1999, William Dunham, Euler: The Master of Us All, Mathematical Association of America 1999, p. 64:

     By Cases 1 and 2, we see that any finite collection of 4k – 1 primes cannot contain all such primes. Thus there are infinitely many primes of this type. Q.E.D.

When used to end a mathematical proof, QED is somewhat archaic or traditional; textbooks often use a graphical symbol instead. Further, other languages generally use a vernacular abbreviation, such as French CQFD (“ce qu'il fallait démontrer”); QED is primarily used in English and Hungarian.

• (what was to be demonstrated): QEF

QED (uncountable)

1. Initialism of quantum electrodynamics.
   • 2011, Brian Cox & Jeff Forshaw, The Quantum Universe, Allen Lane 2011, p. 176:

     QED is the theory that explains how electrically charged particles, like electrons, interact with each other and with particles of light (photons).

• (quantum): QCD

• DEQ

QED

1. QED (“quod erat demonstrandum”) Initialism of quod erat demonstrandum.

• English: QED (“quod erat demonstrandum”)

Borrowed from Latin QED.

QED

1. (sciences) QED

• CQD