How did the term yellow come to mean cowardly or shere is the term yellow streak derived from?

Answer 1

well yellow means chicken and i think the old west people said it. it's a nod to the legendary yellowbelly lizard, a reptile apparently not known for its intestinal fortitude (aka "guts"). The story goes that when confronted, the yellowbelly lizard "exits on its belly as soon as possible."

Answer 2

The term "yellow" meaning cowardly likely originated from the color yellow's association with fear and illness. The term "yellow streak" may come from the idea that a streak of cowardice runs through a person, similar to how a different colored streak might represent a different trait.