any of various large sharks of the genus Alopias, esp A. vulpinus, occurring in tropical and temperate seas: family Alopiidae. They have a very long whiplike tail with which they are thought to round up the small fish on which they feed
thresher in American English
(ˈθrɛʃər)
noun
1.
a person who threshes
2.
threshing machine
3.
any of a family (Alopiidae, order Lamniformes) of large sharks of temperate and tropicalseas, having a very long upper tail lobe, which supposedly threshes the water and drives its prey together