OS/2
OS/2: /O S too/ n. The anointed successor to MS-DOS for Intel
286- and 386-based micros; proof that IBM/Microsoft couldn't get it
right the second time, either. Often called `Half-an-OS'.
Mentioning it is usually good for a cheap laugh among hackers ---
the design was so baroque, and the implementation of 1.x so
bad, that 3 years after introduction you could still count the
major apps shipping for it on the fingers of two hands --- in
unary. The 2.x versions are said to have improved somewhat, and
informed hackers now rate them superior to Microsoft Windows (an
endorsement which, however, could easily be construed as damning
with faint praise). See monstrosity, cretinous,
second-system effect.