Ray Denenberg, Library of Congress wrote:
Leaving aside metasearch and broadcast search (terms invented more recently) it is a shame if "federated" has really lost its distinction from"distributed". Historically, a federated database is one that integrates multiple (autonomous) databases so it is in effect a virtual distributed database, though a single database. I don't think that's a hard concept and I don't think it is a trivial distinction.
For at least 10 years vendors in the library market have been selling us products called "federated search" which are in fact distributed/broadcast search products.
If you want to reclaim the term "federated" to mean a local index, I think you have a losing battle in front of you.
So I'm sticking with "broadcast search" and "local index". Sometimes you need to use terms invented more recently when the older terms have been used ambiguously or contradictorily. To me, understanding the two different techniques and their differences is more important than the terminology -- it's just important that the terminology be understood.