terminus a quo vs commencement

terminus a quo and commencement both are nouns.

Word	Noun	Adjective	Verb	Adverb
terminus a quo	Yes	No	No	No
commencement	Yes	No	No	No

As nouns, commencement is a hypernym of terminus a quo; that is, commencement is a word with a broader meaning than terminus a quo:

Other hypernyms of terminus a quo include beginning, first, get-go, kickoff, offset, outset, showtime, start, starting time.

terminus a quo (noun)	commencement (noun)
earliest limiting point	the act of starting something
	an academic exercise in which diplomas are conferred
	the time at which something is supposed to begin