BerkeleySoftwareDistribution, or perhaps BusinessSystemsDevelopments.

"*BSD" is often used when talking about FreeBSD, NetBSD and OpenBSD as a group. They all originally came from the same source code, the Berkeley Software Distribution from the University of Calfornia, Berkeley. BSD4.2 was perhaps the most influential version. Released in the early 1980's (1983, 1984?). They are all released under the BSD License?.

Has a few Free distributions:

• FreeBSD FreeBSD.org
  FreeBSD is an advanced operating system for Intel ia32 compatible, DEC Alpha, and PC-98 architectures. It is derived from BSD UNIX, the version of UNIX developed at the University of California, Berkeley.
• NetBSD
  NetBSD is a free, secure, and highly portable UNIX-like operating system available for many platforms, from 64-bit AlphaServers and desktop systems to handheld and embedded devices.
• OpenBSD
  The OpenBSD project produces a FREE, multi-platform 4.4BSD-based UNIX-like operating system. Our efforts emphasize portability, standardization, correctness, proactive security and integrated cryptography.

and a few others:

• BSDi
• Berkeley DataBase

etc...

As quoted by fortune(6): There are two major products that come out of Berkeley: LSD and UNIX. We don't believe this to be a coincidence. -- Jeremy S. Anderson

Good things Berkeley gave us:

• TCP/IP (aka Berkeley sockets) and related tools
• GEOS for the Commodore 64

Bad things Berkeley gave us:

• csh(1)

Yet Another Three Letter Acronym

See also CategoryOperatingSystem