Is first an adjective or noun?

"First" can be both an adjective and an adjective. It depends on how it's used in a sentence.

Adjective:

* "She was the first person to arrive." Here, "first" describes the person, making it an adjective.

Noun:

* "They came in first place." Here, "first" refers to the position, making it a noun.

In short, "first" is a flexible word that can function as both an adjective and a noun, depending on its role in the sentence.