Webster's Revised Unabridged Dictionary · 1913

Yellowtail

Yellowtail , noun

(a)
(Zoology) Any one of several species of marine carangoid fishes of the genus Seriola; especially, the large California species (Seriola dorsalis) which sometimes weighs thirty or forty pounds, and is highly esteemed as a food fish; -- called also cavasina, and white salmon.
(b)
(Zoology) The mademoiselle, or silver perch.
(c)
(Zoology) The menhaden.
(d)
(Zoology) The runner, 12.
(e)
(Zoology) A California rockfish (Sebastodes flavidus).
(f)
(Zoology) The sailor's choice (Diplodus rhomboides).

Several other fishes are also locally called yellowtail.