Though it might also sound like the name of a short-lived 1990s jukebox manufacturer whose products only played songs from Nirvana and Soundgarden, in a financial context "altcoin" refers to crypto-currencies other than Bitcoin. The term (as in "alternative to Bitcoin") gained traction as a way to distinguish other crypto players from the industry's most well-known participant. Like how Altnex refers to non-Kleenex facial tissue. See our opus on Bitcoin for details.