What part of speech is ex?

"Ex" can be a few different parts of speech depending on how it's used:

* Adjective: Describing a former spouse, partner, employee, etc. (e.g., "my ex-husband", "an ex-employee")

* Noun: Short for "ex-boyfriend" or "ex-girlfriend" (e.g., "I ran into my ex at the store")

* Prefix: Meaning "former" or "previous" (e.g., "ex-president", "ex-wife")

So, the specific part of speech for "ex" depends on its context in a sentence.