What part of speech is outbreak?

"Outbreak" can be either a noun or a verb, depending on how it's used in a sentence.

* Noun: When referring to a sudden occurrence of a disease or something else undesirable, it's a noun.

* Example: "The recent outbreak of measles is a cause for concern."

* Verb: When referring to the act of suddenly appearing or starting, it's a verb.

* Example: "The fighting outbreak on the streets."

So, to determine the part of speech, look at the context!