c.1300, from Old French comencier "to begin, start" (10c., Modern French commencer), from Vulgar Latin *cominitiare, originally "to initiate as priest, consecrate," from Latin com- "together" (see com-) + initiare "to initiate," from initium (see initial, adj.). Spelling with double -m- began in French and was established in English by 1500. Related: Commenced; commencing.