"large shallow vessel or dish used chiefly to hold water or other liquid," c. 1200, from Old French bacin (11c., Modern French bassin), from Vulgar Latin *baccinum (source also of Spanish bacin, Italian bacino), from *bacca "water vessel," perhaps originally Gaulish (but OED dismisses the proposed Celtic cognates on sense grounds). Meaning "large-scale artificial water-holding landscape feature" is from 1712. Geological sense of "tract of country drained by one river or draining into one sea" is from 1830.