what part of the term 'Killer-Whale' do you not understand?

TILLIKUM the 'Killer-Whale' at SeaWorld in Orlando Florida has ended the life of one of his trainer's. TILLIKUM is a wild animal 'trained' to perform for spectators. For whatever reason whether through the trainer's own negligence or because of the animal's nature - a death occurred. WHAT DO WE NOT UNDERSTAND WHEN WE DESIGNATE THIS 'ORCA'(Orcinus orca - a very efficient predator in the ocean's of the world) AS A 'KILLER-WHALE'??? We have become immune to the 'lion-tamer-putting-his-head-into-the-lion/tiger's-mouths' to thrill us - we as the audience seek more spectales more risks - this is unfortunately sometimes the result for our prurient lustings of mankind versus beast.