1A dog used for hunting or baiting bears and other animals. In later use specifically (in full "Karelian bear dog"): a spitz type dog of a breed developed in Finland for hunting bears and other large game, having a black and white coat with a curled tail.
2Any of various extinct mammals combining attributes of dogs and bears; especially a carnivore of the family Amphicyonidae, widespread during the Miocene epoch.
Bear dogs are distantly related to dogs and bears, but are not considered to be their direct evolutionary ancestors.
Late 16th century (in an earlier sense). From bear + dog.