look up any word, like cunt:
 
1.

Verb:
To begin happening, or begin something, to start.

The year's commences are at the 1st of Januari.
by Jafje April 18, 2007
 
2.
the act of initiating the consumption of alcoholic beverages, quickly and efficiently
Hey Dana and Joel, Let us commence. It is Thursday!
by commencer extrodinaire November 19, 2010