reject vs turn down

reject is a noun but turn down is not a noun.

Word	Noun	Adjective	Verb	Adverb
reject	Yes	No	Yes	No
turn down	No	No	Yes	No

As verbs, reject and turn down are synonyms defined as:

Other synonyms of reject include disdain, freeze off, pooh-pooh, scorn, spurn.

As verbs, reject and turn down are synonyms defined as:

Other synonyms of reject include decline, pass up, refuse.

As verbs, reject and turn down are synonyms defined as:

Other synonyms of reject include refuse, turn away.

reject (noun)	turn down (noun)
the person or thing that is rejected or set aside as inferior in quality

reject (verb)	turn down (verb)
not accept something given or offered	make lower or quieter
dismiss from consideration or a contest	take a downward direction
deem wrong or inappropriate	reject with contempt
reject with contempt	not accept as true
not accept as true	refuse entrance or membership
refuse entrance or membership
resist immunologically the introduction of some foreign tissue or organ