tunny

[Italian tonno or French thon, both from Old Provençal ton, from Latin thynnus, from Greek thunnos.]

The noun has 2 meanings:

Meaning #1: important warm-water fatty fish of the genus Thunnus of the family Scombridae; usually served as steaks
  Synonyms: tuna, tuna fish

Meaning #2: any very large marine food and game fish of the genus Thunnus; related to mackerel; chiefly of warm waters
  Synonym: tuna