extremum vs minimum

extremum and minimum both are nouns.

Word	Noun	Adjective	Verb	Adverb
extremum	Yes	No	No	No
minimum	Yes	Yes	No	No

As nouns, minimum is a hyponym of extremum; that is, minimum is a word with a more specific, narrower meaning than extremum:

Other hyponyms of extremum include lower limit, maximum, upper limit.

extremum (noun)	minimum (noun)
the point located farthest from the middle of something	the point on a curve where the tangent changes from negative on the left to positive on the right
the most extreme possible amount or value	the smallest possible quantity

extremum (adjective)	minimum (adjective)
	the least possible