from The American Heritage® Dictionary of the English Language, 4th Edition
- abbr. Latin quod erat faciendum (which was to have been done)
from Wiktionary, Creative Commons Attribution/Share-Alike License
- “quod erat faciendum”, “what was to have been done” – used to end a mathematical passage other than a proof.
Latin quod erat faciendum ("what was to have been done"), from Ancient Greek ὅπερ ἔδει ποιῆσαι (hoper edei poiēsai). (Wiktionary)