Other forms: commenced, commencing, commences
To commence is the formal word for to begin. Commence proceedings, work will commence, commence at nine.
It belongs to notices, contracts and ceremonies, and using it in ordinary speech sounds stiff — start does the job. Commence proceedings is the standard legal phrase for beginning a case. Note commencement, which in British English means the beginning and in American English means the graduation ceremony, from the idea that graduating is the start of something rather than the end.
commence is a beginning.
Also accepted in games: start
Latin com- plus initiare, to begin — from initium, a beginning. The same initium gives initial, initiate and initiative, all about starting something.
Latin
com-
Vulgar Latin
*cominitiāre
Anglo-Norman
comencier
Middle English
commencen
English, today
commence
From Middle English commencen, comencen (also as contracted comsen, cumsen), from Anglo-Norman comencier, from Vulgar Latin cominitiāre, formed from Latin com- + initiō (whence English initiate).
Etymology from Wiktionary, CC BY-SA