Is a candidate master considered a master? Is an FIDE candidate master (CM) considered a master? For example, if two opponents are each rated 2250 by the FIDE and each is a CM, is their game considered a master game?

In ordinary English, the title candidate master would seem to say, "not yet a master," but I do not know what chess convention thinks of it. This is why I ask.
In the strict realm of FIDE, a 2200 FIDE rated CM is not a master. This is because FIDE's official master title is the FM (2300 FIDE rating).

However, in the US and Canada, a 2200 national rating earns the NM (national master) title. So, if a player had a 2200 FIDE rating but a 2100 national rating, in the strict sense they would not be considered a master. To be a master you must meet the requirements of FIDE or your country's federation.

Most chess players aren't aware of these arbitrary rating thresholds though, and it's likely they would consider anyone with a 2200 rating in whatever system a master (even though this may not be officially true).