[waterhouse]

I personally just say Mac OS. If there were some device called the Blarg, with an operating system built to run just on the Blarg, then that operating system would be most naturally called Blarg OS; I suspect the vast majority of people would call it that if no name were supplied.

[Wowfunhappy]

Also, since OS X's full name was always still "Mac OS X", "Mac OS" correctly refers to every iteration of the operating system.