incline vs let down

incline is a noun but let down is not a noun.

Word	Noun	Adjective	Verb	Adverb
incline	Yes	No	Yes	No
let down	No	No	Yes	No

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

Other hypernyms of incline include bring down, get down, lower, take down.

incline (noun)	let down (noun)
an inclined surface connecting two levels
an elevated geological formation

incline (verb)	let down (verb)
make receptive or willing towards an action or attitude or belief	fail to meet the hopes or expectations of
feel favorably disposed or willing	move something or somebody to a lower position
be at an angle
lower or bend (the head or upper body), as in a nod or bow
bend or turn (one's ear) towards a speaker in order to listen well
have a tendency or disposition to do or be something; be inclined