What part of speech is the word third?

"Third" can be a few different parts of speech depending on its use in a sentence:

* Ordinal number: When it indicates position in a sequence (e.g., "the third day of the week").

* Adjective: When it modifies a noun (e.g., "the third time is the charm").

* Noun: When it refers to the number itself (e.g., "a third of the students").

Let me know if you have a specific sentence in mind, and I can tell you exactly what part of speech "third" is in that sentence!