WordNet (r) 3.0 (2006):

bbs
    n 1: a computer that is running software that allows users to
         leave messages and access information of general interest
         [syn: bulletin board system, bulletin board,
         electronic bulletin board, bbs]

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

BBS
       Bulletin Board System (telecommunication)


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

BBS
 /B?B?S/, n.

    [common; abbreviation, ?Bulletin Board System?] An electronic bulletin
    board system; that is, a message database where people can log in and leave
    broadcast messages for others grouped (typically) into topic groups. The
    term was especially applied to the thousands of local BBS systems that
    operated during the pre-Internet microcomputer era of roughly 1980 to 1995,
    typically run by amateurs for fun out of their homes on MS-DOS boxes with a
    single modem line each. Fans of Usenet and Internet or the big commercial
    timesharing bboards such as CompuServe and GEnie tended to consider local
    BBSes the low-rent district of the hacker culture, but they served a
    valuable function by knitting together lots of hackers and users in the
    personal-micro world who would otherwise have been unable to exchange code
    at all. Post-Internet, BBSs are likely to be local newsgroups on an ISP;
    efficiency has increased but a certain flavor has been lost. See also 
    bboard.


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

bulletin board system
bboard
BBS
bulletin board
CBBS
message board

    (BBS, bboard /bee'bord/, message
   board, forum; plural: BBSes) A computer and associated
   software which typically provides an electronic message
   database where people can log in and leave messages.  Messages
   are typically split into topic groups similar to the
   newsgroups on Usenet (which is like a distributed BBS).
   Any user may submit or read any message in these public areas.

   The term comes from physical pieces of board on which people
   can pin messages written on paper for general consumption - a
   "physical bulletin board".  Ward Christensen, the programmer
   and operator of the first BBS (on-line 1978-02-16) called it a
   CBBS for "computer bulletin board system".  Since the rise of
   the World-Wide Web, the term has become antiquated, though
   the concept is more popular than ever, with many websites
   featuring discussion areas where users can post messages for
   public consumption.

   Apart from public message areas, some BBSes provided archives
   of files, personal electronic mail and other services of
   interest to the system operator (sysop).

   Thousands of BBSes around the world were run from amateurs'
   homes on MS-DOS boxes with a single modem line each.
   Although BBSes were traditionally the domain of hobbyists,
   many connected directly to the Internet (accessed via
   telnet), others were operated by government, educational,
   and research institutions.

   Fans of Usenet or the big commercial time-sharing bboards
   such as CompuServe, CIX and GEnie tended to consider
   local BBSes the low-rent district of the hacker culture, but
   they helped connect hackers and users in the personal-micro
   and let them exchange code.

   Use of this term for a Usenet newsgroup generally marks one
   either as a newbie fresh in from the BBS world or as a real
   old-timer predating Usenet.

   (2005-09-20)