n. Relating to transactions in which a business sells a service or product to a consumer using another business as an intermediary.
Another general message to the believers was: B2B (business-to-business marketing) and B2C (business to consumer) are so five minutes ago; from now on it's all about B2B2C.
—Jessica Seigel, “While Nasdaq Burns,” The New York Times, April 23, 2000
First there was B2B, short for business-to-business Internet companies like Ariba and Commerce One.

Then came B2C, applied retroactively to business-to-consumer companies like Amazon.com, Yahoo or America Online.

The next logical step was C2C, a nickname for consumer-to-consumer companies like eBay.

Now get ready for (drum roll, please) B2B2C.
—Kathleen Pender, “Whatever B2B2C Means, One Thing is Clear — It's the Place 2B,” The San Francisco Chronicle, April 11, 2000
1999 (earliest)
OrderTrust likes to think of itself in a separate space to the business-to-business players like Ariba and Commerce One; it says it is in the "b2b2c space" meaning that it enables businesses to connect to businesses and then sell things to consumers.
—Nick Patience, “OrderTrust Will Enable Merchants to 'Cherry-Pick' Products,” Computergram International, September 27, 1999
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