he lost his nerve

[keannu]

Does this "nerve" refer to "courage" or "gall"? There are two similar definitions for this, and do they mean similar things?

go2-41)One day Howard Kelly, a poor boy, who was selling goods from door to door to pay his way through school, found he had only one thin dime left, and he was hungry. He decided he would ask for a meal at the next house. However, he lost his nerve when Grace, a lovely young woman, opened the door. Instead of a meal he asked for a drink of water.

[5jj]

There aren't two conflicting definitions for 'lose one's nerve' in most of the dictionaries I looked through.