(1) A programming interface in the PowerPC versions of the Mac OS X operating system that supported earlier, non-Unix Mac OS 9 applications. Originally called the "Blue Box," Classic was dropped in the Intel versions of OS X and later for the PowerPC with the Version 10.5 (Leopard) of OS X. See Mac OS X.

(2) A Mac or Mac operating system prior to Mac OS X.

(3) A modernized remake of the original "hi-rise" Macintosh. The Classic came out in 1990. See Macintosh models - early.