curb vs restrain

curb is a noun but restrain is not a noun.

Word	Noun	Adjective	Verb	Adverb
curb	Yes	No	Yes	No
restrain	No	No	Yes	No

As verbs, restrain is a hypernym of curb; that is, restrain is a word with a broader meaning than curb:

curb: keep to the curb
restrain: restrict (someone or something) so as to make free movement difficult

Other hypernyms of curb include cumber, encumber.

As verbs, restrain is a hypernym of curb; that is, restrain is a word with a broader meaning than curb:

curb: lessen the intensity of; temper; hold in restraint; hold or keep within limits
restrain: prevent the action or expression of

Other hypernyms of curb include hold back, keep, keep back.

curb (noun)	restrain (noun)
the act of restraining power or action or limiting excess
an edge between a sidewalk and a roadway consisting of a line of curbstones (usually forming part of a gutter)
a horse's bit with an attached chain or strap to check the horse

curb (verb)	restrain (verb)
place restrictions on	prevent the action or expression of
keep to the curb	to close within bounds, or otherwise limit or deprive of free movement
lessen the intensity of; temper; hold in restraint; hold or keep within limits	restrict (someone or something) so as to make free movement difficult
	prevent (someone or something) from doing something