[1] : The Collaborative International Dictionary of English v.0.48

tuna \tu"na\, n. bot.
   the opuntia tuna. see prickly pear, under prickly.
   1913 webster
see also:
opuntia tuna prickly pear prickly 

[2] : The Collaborative International Dictionary of English v.0.48

tuna \tu"na\, n. cf. tunny.
   1. zool. any one of several species of large oceanic fishes
      belonging to the mackerel family scombridae, especially
      the bluefin tuna thunnus thynnus, formerly orcynus
      thynnus or albacora thynnus, called also the common
      tunny or great tunny, a native of the mediterranean sea
      and of temperate parts of the atlantic ocean. it sometimes
      weighs a thousand pounds or more, and is caught
      commercially in large quantity for use as food; -- also
      called, especially in britain, tunny. it is also one of
      the favorite fishes used by the japanese in preparing
      sushi. on the american coast, especially in new england,
      it is sometimes called the horse mackerel. another
      well-known species is the yellowfin tuna thunnus
      albacares of warm seas. the see illust. of horse
      mackerel, under horse.

   note: the little tunny gymnosarda alletterata of the
         mediterranean and north atlantic, and the long-finned
         tunny, or albacore thunnus alalunga see
         albacore, are related species of smaller size.
         1913 webster +pjc

   2. the bonito, 2.
      1913 webster

   3. the meat of the tuna, used as food; -- also called tuna
      fish.
      pjc
see also:
tunny scombridae bluefin tuna thunnus thynnus orcynus thynnus albacora thynnus 
common tunny great tunny tunny horse mackerel yellowfin tuna 
thunnus albacares horse mackerel horse gymnosarda alletterata thunnus alalunga 
albacore tuna fish 

[3] : The Collaborative International Dictionary of English v.0.48

tunny \tun"ny\ tu^n"ny^, n.; pl. tunnies. l. thunnus,
   thynnus, gr. qy`nnos, qy^nos: cf. it. tonno, f.  pr. thon.
   zool.
   the chiefly british equivalent of tuna; any one of several
   species of large oceanic fishes belonging to the mackerel
   family, especially the common or great tunny thunnus
   thynnus syn. albacora thynnus, formerly orcynus 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. written also thynny.
   1913 webster

   note: the little tunny gymnosarda alletterata of the
         mediterranean and north atlantic, and the long-finned
         tunny, or albicore thunnus alalunga, see
         albacore, are related species of smaller size.
         1913 webster
see also:
tunnies tuna thunnus thynnus albacora thynnus orcynus thynnus horse mackerel 
horse mackerel horse thynny gymnosarda alletterata thunnus alalunga 
albacore 

[4] : WordNet (r) 2.0

tuna
     n 1: tropical american flat-jointed prickly pear; jamaica syn: opuntia
          tuna
     2: important warm-water fatty fish of the genus thunnus of the
        family scombridae; usually served as steaks syn: tuna
        fish, tunny
     3: any very large marine food and game fish of the genus
        thunnus; related to mackerel; chiefly of warm waters syn:
         tunny
     4: new zealand eel syn: anguilla sucklandii
see also:
opuntia tuna tuna fish tunny anguilla sucklandii 

Tuna >> T Words
Tuna, definition of term: Tuna
tuna_pag1.html

Tuna Fish >> T Words
Tuna Fish, definition of term: Tuna Fish
tuna+fish_pag1.html

Skipjack Tuna >> S Words
Skipjack Tuna, definition of term: Skipjack Tuna
skipjack+tuna_pag1.html