The Collaborative International Dictionary of English v.0.48:

Mos \Mos\, n.,
   sing. of Mores. [Rare]
   [Webster 1913 Suppl. +PJC]

The Collaborative International Dictionary of English v.0.48:

Mores \Mo"res\ (m[=o]"r[=e]z), n. pl.; sing. Mos (m[=o]s).
   [L.]
   Customs; habits; esp., moral customs conformity to which is
   more or less obligatory; customary law. [singular is rarely
   used]
   [Webster 1913 Suppl. +PJC]

V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

MOS
       Master Operating System (OS, Varian)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

MOS
       Minimum Operating System (OS, UNIVAC 9200, UNIVAC 9300)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

MOS
       Metal Oxide Semiconductor (IC)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

MOS
       Multiprogramming Operating System (OS, NCR)


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

Metal Oxide Semiconductor
MOS

    (MOS) The three materials used to form a gate
   in the most common kind of Field Effect Transistor - a
   MOSFET.

   [Other MOS devices?]

   (1996-05-27)