gird vs build up

gird and build up both are verbs.

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

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

Other synonyms of gird include arm, fortify.

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