Stagnation is a noun.
part of speech
The part of speech for this particular word is a noun.
adverb
what part of speech is work
what part of speech is beneath
the part of speech sashay is a averb
Did is a verb, and not is an adverb. Didn't is not any part of speech. It's a contraction of did and not.
to prevent mental stagnation, you have to be alert. physically and mentally!!! that's it.
The official definition of the word stagnation is "the state of being still, or not moving."
Adjective
The word speech is a noun.
No, but it's part of a noun which the noun is the part of speech.