Is the word not an adjective?

You're right! "Not" is not an adjective. It's a negation, a word that makes a statement negative.

Here's why:

* Adjectives describe nouns: They tell us more about a person, place, or thing. For example: "red car," "happy child," "tall building."

* "Not" modifies verbs, adjectives, or other adverbs: It negates the meaning of the word it's attached to. For example: "He is not happy," "The car is not red," "She did not run fast."

Let me know if you have any more questions about parts of speech!