Please, omit explaining what RSS channel or feed is. This is familiar for me.
The first use of the word syndication as part of the abbreviation “RSS” is the September 2002 release of “Really Simple Syndication” (RSS 2.0). Earlier versions of this protocol had been called “Rich Site Summary” and “RDF Site Summary”. The origin of the new name was the author of RSS 2.0, Dave Winer.
But Winer’s use of the word syndication, meaning the generation of a specially formatted edition of a website that a portal or aggregator could easily republish, goes back at least to his 1999 article “Syndication in XML”, published on his website, Scripting News.
So Vignette went the next step, and took the lead in what was then a new technology for the web, syndication. Last year they released a specification thru the W3C called ICE. With an ICE-compatible server, ZDNet could now publish their content, without ads, and sell republishing rights to portals. It was a clever business for Vignette, because it furthered dependence on their software, and if it caught on, it would create new customers for their software, the portals.
The solutions will be centered around Vignette's products such as StoryServer and Vignette Syndication Server and will involve considerable integration with other products and platforms in the Internet environment.
Winer mentioned The Information and Content Exchange (ICE) Protocol released through W3C and dated October 1998 that makes extensive use of the terms syndication and syndicators. For example:
This document describes the Information and Content Exchange protocol for use by content syndicators and their subscribers. The ICE protocol defines the roles and responsibilities of syndicators and subscribers, defines the format and method of content exchange, and provides support for management and control of syndication relationships. We expect ICE to be useful in automating content exchange and reuse, both in traditional publishing contexts and in business-to-business relationships.
"Syndicated feeds" when used in web, in fact, refers to "web syndication" through "rss feed" in which website material is made available to / from multiple other sites.
For more information please check wikipedia
The pertinent definition is:
[transitive usually passive] to arrange for written work, photographs etc to be sold to a number of different newspapers, magazines etc:
His column is syndicated throughout America.
This practice goes way back into the history of newspapers and magazines (I haven't researched how far).
What happens is that a columnist/cartoonist/whatever creates content. He enters into a number of contracts with newspapers/magazines, to whom he sends the content on a regular basis, so that they may publish it.
RSS's "syndication" is analogous to this. The RSS feed is the "cartoonist", and the software that subscribes to the feed is the "newspapers".