What is "hardtail"

Jurel \Ju"rel\, n. (Zo["o]l.) A yellow carangoid fish of the Atlantic and Gulf coasts ( Caranx chrysos), most abundant southward, where it is valued as a food fish; -- called also hardtail, horse crevall['e], jack, buffalo jack, skipjack, yellow mackerel, and sometimes, improperly, horse mackerel. Other species of Caranx (as Caranx fallax) are also sometimes called jurel.

n. 1 jack (gloss: edible fish of the genus ''Caranx'' or ''Trachurus'') 2 A bicycle or motorcycle without rear suspension.