What does "q.e.d." mean?

A certain fact or scenario that proves an argument or proposition; a justification.

What is a synonym for "q.e.d."?

Common synonyms include: wwwww.

Pronounced //ˌkjuːiːˈdiː//.

//ˌkjuːiːˈdiː// noun, phrase

noun, phrase ·Rare ·Advanced level

Noun

1
A certain fact or scenario that proves an argument or proposition; a justification.
"We all go in for the dolce here except you, and you're such a patent machine for turning out Q.E.D.s by the dozen, that you can no more help working than the bedmaker can help taking my tea and saying the cat did it,[…]"

Phrase

1
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. abbreviation, alt-of, dated, initialism
"[A]fter the same manner S and U are proved to be equal, therefore the square of CB is equal to the square of the 2 other sides Q E D."
2
Alternative letter-case form of Q.E.D.. alt-of
"Now let any right line meet four harmonicals in A, C, B, D, and if thoſe harmonicals be parallel, the thing is evident; but, if they interſect in V, draw ECF parallel to VD, the line moſt remote from C; then, by the firſt part, EC#61;CF, and AD#58;AC#58;#58;VD#58;EC or CF. Therefore AD#58;AC#58;#58;BD#58;CB. q.e.d."
3
Used to indicate that an argument or proposition is proved by the existence of some fact or scenario. broadly
"That this part of the world has actually been peopled (Q. E. D.) to support which, we have living proofs in the numerous tribes of Indians that inhabit it."

"[A]fter the same manner S and U are proved to be equal, therefore the square of CB is equal to the square of the 2 other sides Q E D."

From Late Latin QED, from Latin quod erat demonstrandum.

Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.