The Free On-line Dictionary of Computing (30 December 2018):

MultiTOS

    (MTOS) A new version of TOS.  MultiTOS's
   main advantage was support for pre-emptive multitasking and
   memory protection.  It also supported the latest (and far
   superior) versions of GEM.  MultiTOS was supplied with the
   Falcon030 range of computers from Atari.

   It is a little known fact that the MultiTOS kernel was based
   heavily on the freeware OS MinT which was developed long
   before Atari got MultiTOS working.

   (1997-01-10)