Webster's Revised Unabridged Dictionary · 1913

Thrash

Thrash , transitive verb

[Old English þreschen, þreshen, to beat, Anglo-Saxon þerscan, þrescan; akin to Dutch dorschen, OD. derschen, German dreschen, Old High German dreskan, Icelandic þreskja, Swedish troska, Danish tarske, Gothic þriskan, Lithuanian traszketi to rattle, Russ. treskate to burst, crackle, tresk' a crash, OSlav. troska a stroke of lighting. Compare Thresh.]

1.
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.
The wheat was reaped, thrashed, and winnowed by machines. — H. Spencer
2.
To beat soundly, as with a stick or whip; to drub.

Also: Thresh

Thrash , transitive verb

1.
To practice thrashing grain or the like; to perform the business of beating grain from straw; as, a man who thrashes well.
2.
Hence, to labor; to toil; also, to move violently.
I rather would be Maevius, thrash for rhymes, Like his, the scorn and scandal of the times. — Dryden

Also: Thresh