The Collaborative International Dictionary of English v.0.48:

Bonito \Bo*ni"to\ (b[-o]*n[=e]"t[-o]), n.; pl. Bonitoes
   (-t[-o]z). [Sp. & Pg. bonito, fr. Ar. bain[imac]t and
   bain[imac]th.] [Often incorrectly written bonita.] (Zool.)
   1. A large tropical fish (Orcynus pelamys) allied to the
      tunny. It is about three feet long, blue above, with four
      brown stripes on the sides. It is sometimes found on the
      American coast.
      [1913 Webster]

   2. any of a variety of scombroid fishes of the genera Sarda
      or Euthynnus, with a size intermediate between those of
      the smaller mackerels and the tunas. It is applied
      especially to the skipjack tuna (Euthynnus pelamis,
      syn. Katsuwonus pelamis, formerly Sarda Mediterranea,
      also called skipjack) of the Atlantic, an important and
      abundant food fish on the coast of the United States, and
      (Sarda Chilensis) of the Pacific, and other related
      species. These are large and active fishes, of a blue
      color above and silver below, with black oblique stripes.
      --MW10
      [1913 Webster +PJC]

   3. The medregal (Seriola fasciata), an edible fish of the
      southern part of the United States and the West Indies.
      [1913 Webster]

   4. The cobia or crab eater (Elacate canada), an edible fish
      of the Middle and Southern United States.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Euthynnus pelamis
    n 1: oceanic schooling tuna of considerable value in Pacific but
         less in Atlantic; reaches 75 pounds; very similar to if not
         the same as oceanic bonito [syn: skipjack, skipjack
         tuna, Euthynnus pelamis]