curb vs curtail

curb is a noun but curtail is not a noun.

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

As verbs, curb and curtail are synonyms defined as:

Other synonyms of curb include cut back, restrict.

curb (noun)	curtail (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)	curtail (verb)
place restrictions on	place restrictions on
keep to the curb	terminate or abbreviate before its intended or proper end or its full extent
lessen the intensity of; temper; hold in restraint; hold or keep within limits