Definition of tosa in US English:



  • A dog of a breed of mastiff originally kept for dogfighting.

    • ‘The Japanese tosa, the dogo argentino and the fila braziliero, must be muzzled but are not found in the UK.’
    • ‘All dogs are potentially dangerous, not just pit bulls and Japanese tosas.’
    • ‘People who own American pit bulls, Japanese tosas, Brazilian filas, and dogo Argentinos will have to muzzle them while they are in public.’
    • ‘We are also concerned that some may think that if a dog is not muzzled, if it is not a fila, a tosa, a dogo, or an American pit bull, less care is required around it.’
    • ‘These include the Brazilian fila, the dogo Argentino, the Japanese tosa, and the American pit bull terrier.’


1940s: from Tosa, the name of a former province in Japan.