build up vs gird

build up and gird both are verbs.

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

As verbs, build up and gird are synonyms defined as:

Other synonyms of build up include arm, fortify.

build up (verb)	gird (verb)
form or accumulate steadily	prepare oneself for a military confrontation
enlarge, develop, or increase by degrees or in stages	bind with something round or circular
change the use of and make available or usable	put a girdle on or around
bolster or strengthen
prepare oneself for a military confrontation