What part of speech is coma?

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

* Noun: When referring to the medical condition, it's a noun. For example: "The patient was in a coma for three days."

* Interjection: When used to express surprise or shock, it's an interjection. For example: "Coma! You won the lottery?!"

It's important to consider the context to determine the correct part of speech.