knock up vs impregnate

knock up and impregnate both are verbs.

Word	Noun	Adjective	Verb	Adverb
knock up	No	No	Yes	No
impregnate	No	No	Yes	No

As verbs, knock up and impregnate are synonyms defined as:

Other synonyms of knock up include bang up, prang up.

knock up (verb)	impregnate (verb)
make pregnant	make pregnant
	fertilize and cause to grow
	infuse or fill completely
	fill, as with a certain quality