An FFRDC is a
Federally-Funded Research and Development Center. These are institutions of fairly pure research and engineering that are contracted by the
U.S. Government to perform various acts of
group mental acrobatics. The purpose of said
cranial tumbling is to produce a
report (usually) or, sometimes the more tangible
design for
something the Gov wants. Lots of times, those somethings involve making another government's
somethings go BOOM.
Some examples? The RAND Corporation is an FFRDC. MITRE, which takes its name from its original moniker of MIT Research Corporation, is a more 'classic' FFRDC - it tends to produce actual systems design documents, whereas RAND is more of a think tank. RAND is much less likely to produce actual objects, blueprints, or specs, and very very likely to produce a printed report of varying size and complexity. Los Alamos National Laboratory and Sandia National Laboratory are members of the club.
There are tons of these organizations lurking around the U.S., congregating near centers of policy and technology. Washington, D.C. has SAIC (although that's really more of a straight contractor). Silicon Valley boasts a number of defense-related computer thinkers. And so on.