"1. Southwestern U.S. an unbranded calf, cow, or steer, esp. an unbranded calf that is separated from its mother.
2. a lone dissenter, as an intellectual, an artist, or a politician, who takes an independent stand apart from his or her associates.
3. (initial capital letter) an electro-optically guided U.S. air-to-ground tactical missile for destroying tanks and other hardened targets at ranges up to 15 mi. (24 km)."
So Maverick is either named after an unbranded calf, an independently minded figure, or a missile. Take your pick.