hump·back / ˈhəmpˌbak/ • n. 1. (also humpback whale) a baleen whale (Megaptera novaeangliae) that has a hump (instead of a dorsal fin) and long white flippers. It is noted for its lengthy vocalizations or “songs.” 2. (also humpback salmon) another term for pink salmon. 3. another term for hunchback.DERIVATIVES: hump·backed adj.