As in verifiable truth - noun
The word "fact" is a noun.
A prepositional phrase.
True is an adjective since it describes a noun, like a true fact.
'Untrue' is an adjective because it describes something, such as 'That fact is untrue.'
part of speech
The part of speech for this particular word is a noun.
The part of speech for "answer" is a noun.
adverb
what part of speech is beneath
The part of speech for "explicit" is an adjective.
The part of speech for "twirl" is a verb.
The part of speech for "unfamiliar" is an adjective.