The Collaborative International Dictionary of English v.0.48:

Scombroid \Scom"broid\ (sk[o^]m"broid), a. [Scomber + -oid.]
   (Zool.)
   Like or pertaining to the Mackerel family. -- n. Any fish of
   the family Scombridae, of which the mackerel (Scomber) is
   the type, and including the tuna (Thunnus and related
   genera).
   [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

scombroid
    n 1: important marine food and game fishes found in all tropical
         and temperate seas; some are at least partially endothermic
         and can thrive in colder waters [syn: scombroid,
         scombroid fish]