sweetheart vs knockout

sweetheart and knockout both are nouns.

Word	Noun	Adjective	Verb	Adverb
sweetheart	Yes	Yes	No	No
knockout	Yes	Yes	No	No

As nouns, sweetheart and knockout are synonyms defined as:

Other synonyms of sweetheart include beauty, dish, looker, lulu, mantrap, peach, ravisher, smasher, stunner.

sweetheart (noun)	knockout (noun)
a person loved by another person	a blow that renders the opponent unconscious
a very attractive or seductive looking woman	a very attractive or seductive looking woman
any well-liked individual
a beloved person; used as terms of endearment

sweetheart (adjective)	knockout (adjective)
privileged treatment of a favored person or corporation (sometimes unethically)	very strong or vigorous