Noah Webster's New International Dictionary of the English Language
1. (v. t.) To beat out grain from, as straw or husks; to beat the straw or husk of (grain) with a flail; to beat off, as the kernels of grain; as, to thrash wheat, rye, or oats; to thrash over the old straw.
2. (v. t.) To beat soundly, as with a stick or whip; to drub.
3. (v. t.) To practice thrashing grain or the like; to perform the business of beating grain from straw; as, a man who thrashes well.
4. (v. t.) Hence, to labor; to toil; also, to move violently.
5. (v. t. & i.) Same as Thrash.