thresher

noun

1. a person or thing that threshes.
2. Also thrasher. Also called thresher shark. a large shark of the genus Alopias, especially A. vulpinus, which threshes the water with its long tail to drive together the small fish on which it feeds.

noun

1. a person who threshes
2. short for threshing machine
3. Also called: thrasher, thresher shark 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

n.late 14c., agent noun from thresh. The thresher shark (c.1600) so called for its long upper tail shape, which resembles a threshing tool.