Here are a few possibilities:
* Adjective: This is the most common use, describing a noun. Example: "The weather was perfect for a picnic."
* Verb: It can be used as a verb meaning "to make something flawless." Example: "The team perfected their routine before the competition."
* Noun: It can be used as a noun, usually meaning "the ideal or epitome of something." Example: "This is the perfect example of what we need to avoid."
To know the exact part of speech, you need to look at the context of the sentence.