Proof initials

• "And that proves it"
• "I proved my point"
• Mathematician's "ta-da"
• It is proven monogram
• Relative of "voilà!"
• Logical letters
• Math proof ending
• Mathematician's closing flourish, at times

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
QED \Q.E.D\, QED \QED\(k[=u]"[=e]*d[=e]"), interj. [From Latin, quod erat demonstrandum, i.e. which was demonstrated.] Which was demonstrated; -- a phrase used after the conclusion of some line of reasoning, especially in mathematical or logical proofs. ...

Wikipedia Word definitions in Wikipedia
QED were an Australian New Wave trio, whose lead singer, Jenny Morris , went on to achieve commercial success as a solo artist. The band had a top twenty hit single, "Everywhere I Go", on the Australian Kent Music Report in 1983.