let in vs countenance

let in is not a noun while countenance is a noun.

Word	Noun	Adjective	Verb	Adverb
let in	No	No	Yes	No
countenance	Yes	No	Yes	No

As verbs, countenance is a hypernym of let in; that is, countenance is a word with a broader meaning than let in:

let in: allow participation in or the right to be part of; permit to exercise the rights, functions, and responsibilities of
countenance: consent to, give permission; permit

Other hypernyms of let in include allow, let, permit.

As verbs, countenance is a hypernym of let in; that is, countenance is a word with a broader meaning than let in:

Other hypernyms of let in include allow, let, permit.

let in (noun)	countenance (noun)
	the appearance conveyed by a person's face
	the human face (`kisser' and `smiler' and `mug' are informal terms for `face' and `phiz' is British)
	formal and explicit approval

let in (verb)	countenance (verb)
allow participation in or the right to be part of; permit to exercise the rights, functions, and responsibilities of	consent to, give permission; permit
allow to enter; grant entry to