A nickname of John Francis Anthony Pastorius III (1951-1987), of uncertain origin.According to his father, John Francis Pastorius Jr., the name was derived from when he was in the Navy and later called his son Jaco. Although his brother, Gregory Pastorius, said that the nickname comes from his mother, Stephanie Catherine. His surname may have been influenced by the name Jocko, as Pastorius was a fan for sports as well as the umpire Jocko Conlan (full name John Bertrand Conlan (1899-1989)). In 1974, he began spelling it "Jaco" after it was misspelled by his neighbor, pianist Alex Darqui.