Cold is a noun and an adjective.
Noun: I have a cold.
Adjective: Expect cold weather.
Cold is an adjective in that context.
"cold" is an adjective, and "water" is a noun.
So is an adverb in that example.
Colder is an adjective. It's the comparative form of cold.
Cold is a noun and an adjective. Noun: I have a cold. Adjective: Expect cold weather.
In that usage, it would be an adverb.
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.