What part of speech is every one?

"Every one" can be two different parts of speech depending on how it's used:

* Pronoun: When "every one" refers to each individual in a group, it acts as a pronoun. For example: "Every one of the students passed the test."

* Adjective + Noun: When "every one" means "each and every single one", it acts as an adjective modifying the noun "one". For example: "Every one should be treated with respect."

So, it's important to look at the context to determine the part of speech.