The word "drain" can function as both a noun and a verb. As a noun, it refers to a pipe or channel that carries away liquid, while as a verb, it means to remove liquid from something or to deplete resources. The context in which it is used will determine its part of speech.
part of speech
Adjective
What part of speech is thaw
The part of speech for oscillate is verb.
An adjective is a part of speech.
In this usage, "bathtub" is an adjective, modifying the noun "drain."
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.
The part of speech of "came" is a verb.
The part of speech for "lecturer" is a noun.
The part of speech for "indefinite" is an adjective.