n. One who threshes: in this and the next sense commonly thresher.n. A threshing-machine.n. A sea-fox; a kind of shark, Alopias vulpes, so called from the enormous length of the upper division of the heterocercal tail, with which it threshes the water. See cut under Alopias. In this sense more commonly thrasher.n. A member of an Irish Catholic organization instituted in 1806.n. See thrasher.