narrow vs narrow down

narrow is a noun but narrow down is not a noun.

Word	Noun	Adjective	Verb	Adverb
narrow	Yes	Yes	Yes	No
narrow down	No	No	Yes	No

As verbs, narrow and narrow down are synonyms defined as:

narrow and narrow down: become more focused on an area of activity or field of study

Other synonyms of narrow include specialise, specialize.

As verbs, narrow and narrow down are synonyms defined as:

Other synonyms of narrow include nail down, peg down, pin down, specify.

narrow (noun)	narrow down (noun)
a narrow strait connecting two bodies of water

narrow (adjective)	narrow down (adjective)
not wide
very limited in degree
lacking tolerance or flexibility or breadth of view
characterized by painstaking care and detailed examination
limited in extent or scope

narrow (verb)	narrow down (verb)
make or become more narrow or restricted	become more focused on an area of activity or field of study
become tight or as if tight	define clearly
become more focused on an area of activity or field of study
define clearly