What part of speech is the word half?

The word "half" can be several parts of speech, depending on how it's used in a sentence:

* Adjective: "I ate half the pizza." (Describing the amount of pizza eaten)

* Noun: "Give me half." (Referring to a portion)

* Determiner: "Half the students were absent." (Modifying the noun "students")

* Adverb: "The room was half-empty." (Modifying the adjective "empty")

So, the part of speech for "half" depends on its function in the sentence.