Any one of several species of large oceanic fishes belonging
   to the Mackerel family, especially the common or great tunny (Orcynus /
   Albacora thynnus) native of the Mediterranean Sea and the Atlantic
   Ocean. It sometimes weighs a thousand pounds or more, and is
   extensively caught in the Mediterranean. On the American coast it is
   called horse mackerel. See Illust. of Horse mackerel, under Horse.