The Collaborative International Dictionary of English v.0.48:

Oss \Oss\, v. i. [See Osse, n.]
   To prophesy; to presage. [R. & Obs.] --R. Edgeworth.
   [1913 Webster]

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

OSS
       Open Sound System (Linux, audio)


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

OSS
       Open Source Software (OSS)


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

OSS
       Operator Service System


The Jargon File (version 4.4.7, 29 Dec 2003):

OSS


    Written-only acronym for ?Open Source Software? (see open source). This
    is a rather ugly TLA, and the principals in the open-source movement
    don't use it, but it has (perhaps inevitably) spread through the trade
    press like kudzu.