Etymograph

English

Q.E.D.

Q.E.D. comes from Late Latin QED ‘QED initialism of quod erat demonstrandum’, and goes back to Latin quod erat demonstrandum ‘which was to be proved’.

  1. Latinc. 75 BCE–200 CEquod erat demonstrandum‘which was to be proved’
  2. Late Latinc. 200–600 CEQED‘QED initialism of quod erat demonstrandum’
  3. Englishearliest quotation 1684Q.E.D.

attested reconstructed ? uncertain or disputed

Lineage

  1. Latinc. 75 BCE–200 CEquod erat demonstrandum‘which was to be proved’
  2. Late Latinc. 200–600 CEQED‘QED initialism of quod erat demonstrandum’
  3. Englishearliest quotation 1684Q.E.D.

Earliest quotation: 1684, Mr. Ash, A New and Easy Way of Demonstrating Some Propositions in Euc: “[A]fter the same manner S and U are proved…”

Every English word from Latin quod erat demonstrandum

Today it means

phrase Used to indicate that an argument or proposition is proved by the existence of some fact or scenario.

Language periods are conventional ranges, not dates for this word.

Etymograph / Latin quod erat demonstrandum / Q.E.D.

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