What was the nickname of Hemingway's eldest son?

Hemingway's eldest son was nicknamed Bumby. His full name was John Hadley Nicanor Hemingway, and he was the only child of Ernest Hemingway and his first wife, Hadley Richardson.

The nickname came from his mother, who called him Bumby as a toddler because of his plump, teddy-bear-like appearance. He was born in Toronto in 1923 and spent part of his childhood in Paris and the Austrian Alps, where he grew up around the expatriate literary world associated with his father. Gertrude Stein and Alice B. Toklas were his godparents.

Bumby is easy to confuse with the names of other Hemingway family members. Patrick Hemingway was his younger paternal half-brother, while Gloria Hemingway was his younger paternal half-sister. Jack later became a writer, angler, and conservationist, publishing books on fly fishing. He also served in the U.S. Army during World War II, including work with the Office of Strategic Services, and was briefly held as a prisoner of war.