The story
- Proto-Celtic · derived from*kʷezdis“piece, portion; quota”
- Gaulish · derived from*pettyā
- Late Latin · derived from*pettia
- Old French · derived frompece
- Middle French · derived frompiece
- Anglo-Norman · derived frompece
- Middle English · inherited froma pece
- English todayapiece
Univerbation of a + piece (noun), from Late Middle English a pece. Pece is derived from Anglo-Norman pece, peece, peice, Middle French piece, and Old French pece, pice, piece (“part of a whole”) (modern French pièce); further etymology uncertain, possibly from Late Latin *pettia, *pettium (compare pecia, pecium, petia, petium (“broken piece, fragment; piece of land”)), or from their possible etymon Gaulish *pettyā, from Proto-Celtic *kʷezdis (“piece, portion; quota”).
Etymology from Wiktionary, CC BY-SA 4.0.