buy the farm vs yield

buy the farm is not a noun while yield is a noun.

Word	Noun	Adjective	Verb	Adverb
buy the farm	No	No	Yes	No
yield	Yes	No	Yes	No

As verbs, yield is a hyponym of buy the farm; that is, yield is a word with a more specific, narrower meaning than buy the farm:

buy the farm: pass from physical life and lose all bodily attributes and functions necessary to sustain life
yield: be fatally overwhelmed

Other hyponyms of buy the farm include abort, asphyxiate, stifle, suffocate, buy it, pip out, drown, predecease, famish, starve, fall, succumb.

buy the farm (noun)	yield (noun)
	production of a certain amount
	an amount of a product
	the income or profit arising from such transactions as the sale of land or other property
	the quantity of something (as a commodity) that is created (usually within a given period of time)

buy the farm (verb)	yield (verb)
pass from physical life and lose all bodily attributes and functions necessary to sustain life	end resistance, as under pressure or force
	consent reluctantly
	be willing to concede
	cease opposition; stop fighting
	be flexible under stress of physical force
	give or supply
	cause to happen or be responsible for
	move in order to make room for someone for something
	bring in
	give over; surrender or relinquish to the physical control of another
	be the cause or source of
	give in, as to influence or pressure
	be fatally overwhelmed