mac os x

from The Free On-line Dictionary of Computing (8 July 2008)

Mac OS X

   <operating system> /mak oss ten/ Version 10 of the {Macintosh
   Operating System}, based on {FreeBSD} unlike prevoius
   versions.  Apple released the {kernel} of Mac OS X Server as
   "{darwin}", under an {open source} license.  Mac OS X incldues
   a code {framework} called the "Core Foundation" and an
   "Application Kit" framework for {GUI} and {widgets} strongly
   derived from {NEXTSTEP}.

   (2007-03-15)