Where did the phrase yellow bellied come from?

Answer 1

The phrase "yellow bellied" to mean cowardly is not a terribly easy one to trace. The color yellow has long been associated with treachery and cowardice, and guts (or bellies) with courage and bravery. So the combination of yellow and belly to mean cowardly is fairly intuitive. However, the origins of relating the color yellow to cowardice/treachery is far most obscure. Apparently the doors of traitors were marked with yellow paint in France. In medieval times a yellow star was worn by traitors (a tradition continued by the Nazis to show that Jews were traitors to Jesus). Judas is often portrayed wearing yellow in paintings from the same era. Also, victims of the Spanish Inquisition wore yellow to show that they were traitors. (This information is summarized from http://www.straightdope.com/columns/read/1950/whats-the-origin-of-yellow-bellied, so I won't take credit for knowing any of the above off the top of my head.)