fatten out vs modify

fatten out and modify both are verbs.

Word	Noun	Adjective	Verb	Adverb
fatten out	No	No	Yes	No
modify	No	No	Yes	No

As verbs, modify is a hypernym of fatten out; that is, modify is a word with a broader meaning than fatten out:

Other hypernyms of fatten out include alter, change.

fatten out (verb)	modify (verb)
make fat or plump	make less severe or harsh or extreme
	add a modifier to a constituent
	cause to change; make different; cause a transformation