* Adjective: This is the most common usage, describing something abundant, rich, or luxurious. For example: "The garden was lush with vibrant flowers."
* Verb: Less common, but "lush" can be a verb meaning to grow luxuriantly. For example: "The plants lush in the warm, humid climate."
* Noun: Very rare, but "lush" can be a noun referring to a person who enjoys luxurious living. For example: "He was a known lush, always seeking the finer things in life." (This usage is considered somewhat archaic and is generally avoided.)
So, without context, it's difficult to determine the exact part of speech. You need to look at how it's used in a sentence.