break up vs grind

break up is not a noun while grind is a noun.

Word	Noun	Adjective	Verb	Adverb
break up	No	No	Yes	No
grind	Yes	No	Yes	No

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

Other hyponyms of break up include atomise, atomize, bray, comminute, crunch, mash, pound, sunder, sliver, splinter, rag, crumb, brecciate, crush, grate.

break up (noun)	grind (noun)
	the act of grinding to a powder or dust
	hard monotonous routine work
	the grade of particle fineness to which a substance is ground
	an insignificant student who is ridiculed as being affected or boringly studious

break up (verb)	grind (verb)
laugh unrestrainedly	reduce to small pieces or particles by pounding or abrading
break or cause to break into pieces	make a grating or grinding sound by rubbing together
come to an end	press or grind with a crushing noise
separate (substances) into constituent elements or parts	shape or form by grinding
cause to go into a solution	created by grinding
cause to separate	dance by rotating the pelvis in an erotically suggestive way, often while in contact with one's partner such that the dancers' legs are interlaced
close at the end of a session	work hard
bring the association of to an end or cause to break up
make a break in
set or keep apart
break violently or noisily; smash
attack with or as if with a pickaxe of ice or rocky ground, for example
release ice
destroy the completeness of a set of related items
take apart into its constituent pieces
suffer a nervous breakdown
disband
to cause to separate and go in different directions
discontinue an association or relation; go different ways