The Collaborative International Dictionary of English v.0.48:

Bos \Bos\, prop. n. [L., ox, cow.] (Zool.)
   A genus of ruminant quadrupeds, including the wild and
   domestic cattle, distinguished by a stout body, hollow horns,
   and a large fold of skin hanging from the neck.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Bos
    n 1: wild and domestic cattle; in some classifications placed in
         the subfamily Bovinae or tribe Bovini [syn: Bos, genus
         Bos]

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

BOS
       Basic Operating System (AIX, IBM)


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

BOS
       Basic Overseer Server (AFS)


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

BOS
       Batch Operating System (OS, Honeywell)


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

BOS

   1.  Basic Operating System.

   2.  A data management system written at DESY and used
   in some high energy physics programs.

   3.  The Basic Object System.

   (1999-01-20)