In the chapter "Everyone Knows the King of the Sea," Delphine tells us that "a name is important" because your "name is who you are and how you're known even when you do something great or something dumb."
Delphine had always believed her name was specially chosen for her by her mother, Cecile. Abandoned by Cecile when she was little, Delphine had imagined that her mother had given her the name to make up for the fact that she didn't have a mink coat or ruby earrings to give Delphine. She liked to think that Cecile made up a name that her daughter could grow into. The name Delphine was like a mink coat, a special covering, something only grown women wore. Delphine had found this cherished belief a great comfort; she loved the idea that she didn't have to share this special name with her sisters or with anybody else in the world.
However, she eventually comes to realize that her name can be found in the Merriam-Webster dictionary; even worse, she has been named for a dolphin. This is incredibly distressing to Delphine, and she bursts into tears in the library. She suddenly realizes that her mother didn't pick out a unique name for her after all; it is as if her mother had abandoned her without even bothering to give her a token of her love and regard. After all, her sisters had unique names: Vonetta was named after the singer Sarah Vaughan, and Fern was actually called Afua when she was born. Despite this knowledge, Delphine does not want to give up her name. After all, it is hers alone; she decides to hold on to it for better or for worse.