Is hook a noun or verb?

The Word 'hook' is both a noun (hook, hooks) and a verb (hook, hooks, hooking, hooked).

Examples:

Hang your coat on the hook in the hall. (noun)

We're going to hook a really big fish. (verb)

Don't fall for the hook of a special introductory rate. (noun)

We can hook up after work today. (verb)