c.1200, from O.E. þeah, and in part from O.N. þo "though," both from P.Gmc. *thaukh (cf. Goth. þauh, O.Fris. thach, M.Du., Du. doch, O.H.G. doh, Ger. doch), from PIE demonstrative pronoun *to- (see
that). The evolution of the terminal sound did not follow