What part of speech is the word all?

The word "all" can be a few different parts of speech, depending on its use in a sentence:

* Determiner: This is the most common use of "all." It modifies a noun and tells us about the quantity.

* Example: "All the students are excited for the trip."

* Pronoun: "All" can also act as a pronoun, representing a noun or noun phrase.

* Example: "I ate all of the pizza."

* Adjective: Less commonly, "all" can be used as an adjective, especially when used with a plural noun.

* Example: "The windows were all open."

So, the specific part of speech for "all" depends on its context within a sentence.