Origin

This character combines the body-part radical 月, which looks like meat or an organ, on the left with 旦 on the right, which serves as a sound hint for the pronunciation. The 月 component indicates this character refers to an internal organ, while 旦 provides a rough sound guide for how to say it. The gall bladder is a small organ near the liver, so the shape uses the organ radical to show it's part of the body. Over time, because the gall bladder was associated with courage in ancient beliefs—possibly because brave people were thought to have large ones—the character also came to mean courage and nerve.