Frankly, I much preferred when they called it Mac OS X. The change to OS X just seemed stupid to me—with a name like 'Operating System Ten', it was as if it didn’t even have a name anymore!

…which is why (in my opinion) macOS ('Mac Operating System') is far better than what it’s replacing.

It was called Mac OS for years (1)

I also remember when it was just called "System"

(1) Yeah yeah I know all about NeXT, but OS X isn't NeXT as anyone who used Rhapsody will remember