POS

from The Collaborative International Dictionary of English v.0.48

Compo \Com"po\, n.; pl. {-pos}.
   Short for {Composition}; -- used, esp. in England, colloq. in
   various trade applications; as :
   (a) A mortar made of sand and cement.
   (b) A carver's mixture of resin, whiting, and glue, used
       instead of plaster of Paris for ornamenting walls and
       cornices.
   (c) A composition for billiard balls.
   (d) A preparation of which printer's rollers are made.
   (e) A preparation used in currying leather.
   (f) Composition paid by a debtor.
       [Webster 1913 Suppl.]

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

POS

   {point of sale}

from V.E.R.A. -- Virtual Entity of Relevant Acronyms (June 2006)

POS
       Piece Of Shit (slang, Usenet, IRC)

from V.E.R.A. -- Virtual Entity of Relevant Acronyms (June 2006)

POS
       Primary Operating System (OS, RCA Spectra 70)

from V.E.R.A. -- Virtual Entity of Relevant Acronyms (June 2006)

POS
       Professional Operating System (OS, DEC), "P/OS"

from V.E.R.A. -- Virtual Entity of Relevant Acronyms (June 2006)

POS
       Programmable Object Select