What part of speech is hours?

"Hours" can be a few different parts of speech, depending on how it's used in a sentence:

* Noun: When referring to a unit of time.

* Example: "I worked for hours on that project."

* Adjective: When describing something that lasts for a specific number of hours.

* Example: "It was an hours-long flight."

* Adverb: When modifying a verb or adjective to indicate duration.

* Example: "We talked for hours."

The part of speech will be determined by its function in the sentence.