What part of speech is the word what?

The word "what" can be several parts of speech, depending on its function in a sentence:

* Interrogative pronoun: This is its most common use, asking for information about a person, place, thing, or idea.

* Example: "What is your name?"

* Exclamatory pronoun: Used to express surprise or amazement.

* Example: "What a beautiful day!"

* Relative pronoun: Introduces a relative clause, providing additional information about a noun.

* Example: "I saw the book what you were looking for." (Though this usage is considered less formal and less common in modern English)

So, to determine the part of speech for "what," you need to look at its context within the sentence.