kosher vs proper

kosher is a noun but proper is not a noun.

Word	Noun	Adjective	Verb	Adverb
kosher	Yes	Yes	No	No
proper	No	Yes	No	No

kosher (noun)	proper (noun)
food that fulfills the requirements of Jewish dietary law

kosher (adjective)	proper (adjective)
conforming to Jewish dietary laws	marked by suitability or rightness or appropriateness
proper or legitimate	appropriate for a condition or purpose or occasion or a person's character, needs
	having all the qualities typical of the thing specified
	limited to the thing specified