FAQ is an acronym for Frequently Asked Questions. It is also sometimes used as the singular Frequently Asked Question (Although when was the last time you heard only one question?). Some have called it Frequently Answered Questions as well. This isn't necessarily correct, but it isn't necessarily wrong either. It effectively has the same meaning.
What is a FAQ item?
What are FAQ lists?
How to add FAQ items to lists?
How to use Google Schema Markup?