RINO and DINO: Republican in Name Only, Democrat in Name Only.

These terms are used to describe party members—usually members of Congress—who don't adhere sufficiently to the party line. Both go back a ways. Republican in name only first began appearing in newspaper articles during the 1920s to describe congressmen who went their own way rather than supporting the policies of their Republican president. (Barry Popik's web site traces the term's history.) The acronym RINO is thought to have been invented by California Republican Assembly president Celeste Creig in 1993. Creig created a button with "RINO" and a slash symbol as a way of opposing Los Angeles Mayor Richard Riordan.

Inevitably, DINO came along shortly afterward, around 1994. It isn't heard as often, possibly because the more popular Blue Dog Democrat appeared around the same time. (Blue Dogs, according to the Washington Times for April 21, 1995, are conservative "yellow-dog Democrats turned blue by the choke-hold put on them by their own liberal leadership.")

With the increasing polarization of Congress, RINO and DINO have been getting a workout lately. Two recent examples:
"Call him the last RINO." –Foreign Policy article about Sen. Richard Lugar shortly after he lost his bid to be Indiana's Republican candidate for the Senate, May 8, 2012.
"Incumbent Democrat U.S. Sen. Joe Manchin on Tuesday easily defeated a challenger who called him a DINO – a Democrat in Name Only." –U.S. Senate Examiner article, May 9, 2012.

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