What of part speech is the word certain?

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

* Adjective: Describing something that is definite, sure, or known for sure.

* Example: "I'm certain that the train will be late."

* Pronoun: Referring to some unspecified people or things.

* Example: "Certain people are always late."

* Determiner: Used before a noun to indicate a specific but unidentified thing.

* Example: "Certain events in history are particularly significant."

So, to determine the part of speech of "certain," you need to look at its role in the sentence.