lour vs frown

lour is not a noun while frown is a noun.

Word	Noun	Adjective	Verb	Adverb
lour	No	No	Yes	No
frown	Yes	No	Yes	No

As verbs, lour and frown are synonyms defined as:

lour and frown: look angry or sullen, wrinkle one's forehead, as if to signal disapproval

Other synonyms of lour include glower, lower.

lour (noun)	frown (noun)
	a facial expression of dislike or displeasure

lour (verb)	frown (verb)
look angry or sullen, wrinkle one's forehead, as if to signal disapproval	look angry or sullen, wrinkle one's forehead, as if to signal disapproval
make lower or quieter
set lower