Doorknob is a noun. It names a thing.
Actually, no. Some people actually collect doorknobs, but doorknobs are mostly used for doors.
DIRECT DOOR HARDWARE doorknobs is easiest to install.
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 of "came" is a verb.
The part of speech for "breezy" is an adjective.