A fish family of over 200 species, including pompano, amberjack, bar jack, blue runner, crevalle jack, green jack, horse mackerel (not a true mackerel), rainbow runner, rudderfish, trevally, yellow jack and yellowtail. Although some jack species aren't particularly good to eat, many — particularly pompano — are considered excellent and have a rich, firm, delicately flavored flesh. Jacks are found around the world in the Atlantic, Mediterranean and Pacific. See also fish.