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

NETBIOS
       NETwork Basic Input Output System (IBM, RFC 1001/1002), "NetBIOS"


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

NetBIOS

   An applications programming interface (API) which activates
   network operations on IBM PC compatibles running under
   Microsoft's DOS.  It is a set of network commands that the
   application program issues in order to transmit and receive
   data to another host on the network.  The commands are
   interpreted by a network control program or network
   operating system that is NetBIOS compatible.  See
   NetBOLLIX.