Why yellow color referred to as a cowardly person?

am not aware that yellow represents cowardness..

Says who? every color like every human personality always have their own positive and negative. For yellow as far as I heard, yellow is representing open minded people, feeling of happy, and cheers around life. Even I'm not liking that color much, but I can tell it just by seeing, it has bright effect to everyone whose look into. That's why most of children give yellow as he color of sun. The negative about yellow is representing labile personality, people who can't thinking serious, only joking around also represented by yellow color.

I am not aware that yellow represent a coward person. What I am aware though is NEVER give out yellow roses as it symbolises jealousy and everything bad towards the person you are giving it too. That is the reason I dont give out flowers as I dont bother much about colours, but is afraid the receipient might be sensitive towards it. In my country, YELLOW represents the Royalty. Everything that has got to do with the Royalties are yellow.

Colors represent things. There are many psychology tests based on colors. A simple search for the "meaning of colors" can lead you to different links. This is my first time to hear yellow being used to describe something coward. Psychology and Literature have given society different interpretations of colors. I have always known yellow to depict those extrovert personalities, people who love to be with people, individuals who can easily fit themselves in a new crowd. Generally, yellow in literary pieces means being loyal and faithful to people they love. A lizard is more green than yellow. Color green does not only represent life. It also carries jealousy like "jealousy, the green-eyed monster" used in Shakespeare's Othello. People wrapped in jealousy can be more cowardly when they just cannot fight for what they really want to achieve. I hope your friends were referring to being green not being yellow.