am·ber·jack \ˈ ̷ ̷bə(r)ˌjak\noun (-s) Etymology:amber (I) + jack (fish); from its color 1.: amberfish: as a.: a large vigorous sport fish (Seriola zonata or dumerili) of the western Atlantic from Massachusetts to Brazil b.: a yellowtail (S. dorsalis) 2.: sphalerite