peg down vs narrow down

peg down and narrow down both are verbs.

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

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

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

peg down (verb)	narrow down (verb)
define clearly	become more focused on an area of activity or field of study
fasten or secure with a wooden pin	define clearly