Webster's Revised Unabridged Dictionary · 1913

(Zoology) A name applied to several large fishes of the Mackerel family (Scombridae), esp. Thunnus alalunga (formerly Orcynus alalonga); it is a type of tuna or tunny. The name has been also applied to a larger related species, Thunnus thynnus (formerly Orcynus thynnus), common in the Mediterranean and Atlantic, which is called in New England the horse mackerel.