quod erat demonstrandum (Q.E.D.)

what was to be demonstrated

Notes

The abbreviation is often written at the bottom of a mathematical proof. Sometimes translated loosely into English as "The Five Ws", W.W.W.W.W., which stands for "Which Was What We Wanted".

Words

quod – because, that, the fact that, the point that, what, whereas, which
era – lady, mistress