The word declivity is a noun.
The hill was ideal for beginner skiers because of its gentle declivity
a downward slope.
The side or declivity of a hill.
The part of speech for this particular word is a noun.
part of speech
The part of speech for "answer" is a noun.
what part of speech is beneath
adverb
The part of speech for "explicit" is an adjective.
The part of speech for "lecturer" is a noun.
The part of speech for "rapid" is an adjective.
The part of speech for "breezy" is an adjective.