What is a nickname?

A nickname is a name you call someone that isn't their real name. It can be a short form of their own name, like Rick for Richard or Sal for Sally. It can be an altered version of their name, like Betty or Bets for Elizabeth or Bob for Robert. It can be something you give a friend, like Slim for a thin pal or Tex for someone who comes from Texas. It can be a mean name like Fatso or Dumbo, too. Basically, it's anything you use to refer to a person instead of their birth name.