I'm trying to understand the grammar of this sentence:
Avalanches are dangerous to mountain climbers.
What part of speech is the word mountain?
I'm trying to understand the grammar of this sentence:
Avalanches are dangerous to mountain climbers.
What part of speech is the word mountain?
It is part of the noun phrase "mountain climbers", which is itself the complement of the sentence. Specifically "mountain" is a noun modifier (also called an 'attributive noun' or a 'noun adjunct'), modifying "climbers". A noun modifier is a kind of noun.
In the context of this sentence, "mountain" is an adjective because it modifies (or describes) the noun, "climbers." It tells what kind of climbers they are. Are they tree climbers? No, they are mountain climbers!