build up vs forearm

build up is not a noun while forearm is a noun.

Word	Noun	Adjective	Verb	Adverb
build up	No	No	Yes	No
forearm	Yes	No	Yes	No

As verbs, forearm is a hyponym of build up; that is, forearm is a word with a more specific, narrower meaning than build up:

Other hyponyms of build up include re-arm, rearm.

build up (noun)	forearm (noun)
	the part of the superior limb between the elbow and the wrist

build up (verb)	forearm (verb)
form or accumulate steadily	arm in advance of a confrontation
enlarge, develop, or increase by degrees or in stages
change the use of and make available or usable
bolster or strengthen
prepare oneself for a military confrontation