commence (v.)

c. 1300, "to start, initiate, cause to begin to be" (transitive), from Old French comencier "to begin, to start" (10c., Modern French commencer), from Vulgar Latin *cominitiare, originally "to initiate as priest, consecrate," from Latin com "with, together" (see com-) + initiare "to initiate," from initium "a beginning," literally "a going in," noun use of neuter past participle of inire "to go into, begin," from in- "into, in" (from PIE root *en "in") + ire "to go" (from PIE root *ei- "to go").

From late 14c. in intransitive sense "come into existence, begin to be," also "enter into a new state." Spelling with double -m- began in French and was established in English by 1500. Related: Commenced; commencing.