round down vs alter

round down and alter both are verbs.

Word	Noun	Adjective	Verb	Adverb
round down	No	No	Yes	No
alter	No	No	Yes	No

As verbs, alter is a hypernym of round down; that is, alter is a word with a broader meaning than round down:

Other hypernyms of round down include change, modify.

round down (verb)	alter (verb)
express as a round number	remove the ovaries of
	become different in some particular way, without permanently losing one's or its former characteristics or essence
	cause to change; make different; cause a transformation
	insert words into texts, often falsifying it thereby
	make an alteration to