slack off vs abate

slack off and abate both are verbs.

Word	Noun	Adjective	Verb	Adverb
slack off	No	No	Yes	No
abate	No	No	Yes	No

As verbs, slack off and abate are synonyms defined as:

Other synonyms of slack off include die away, let up, slack.

slack off (verb)	abate (verb)
become less in amount or intensity	become less in amount or intensity
	make less active or intense