It's not a definition set in stone - but it usually refers to a game published by a major publisher, enjoying a large budget (can be millions of dollars) and a large team working on it over a few years.

It's not a definition set in stone - but it usually refers to a game published by a major publisher, enjoying a large budget (can be millions of dollars) and a large team working on it over a few years. AAA titles typically also have a lot of publicity.

The term does not say anything about the game quality or sales figure.