Word Origin & History
thwartc.1200, from O.N. þvert "across," originally neut. of thverr (adj.) "transverse, across," cognate with O.E. þweorh "transverse, perverse, angry, cross," from P.Gmc. *thwerkhaz (cf. M.Du. dwers, Du. dwars "cross-grained, contrary," O.H.G. twerh, Ger. quer, Goth. þwairhs "angry"), altered
(by influence of *thwer- "to turn") from *therkh-, from PIE *twork-/*twerk- "twist" (cf. L. torquere "to twist," Skt. tarkuh "spindle," O.C.S. traku "band, girdle," O.H.G. drahsil "turner," Ger. drechseln "to turn on a lathe"). The verb meaning "oppose, hinder" is mid-13c., from the adv. and prep.