What part of speech is postscript?

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

1. Noun: When referring to the addition at the end of a letter or document, "postscript" is a noun.

* Example: "I added a postscript to my letter explaining the delay."

2. Adjective: When used to describe something as being added after the main part, "postscript" is an adjective.

* Example: "The postscript chapter in the book explained the author's inspiration."

Therefore, the part of speech for "postscript" is determined by its context.