1911 Encyclopædia Britannica/Thrall

THRALL, a slave, a captive or bondman, a term especially applied to the serfs (Lat. servi) of the early northern Teutonic peoples. It only occurs in Old English as a word borrowed from the Norse, the proper term in Old English being “theow” (þreow); the Icel. þraell (Dan. trael, Swed. trâl) is probably represented by O. H. Ger. dregil, trigil, trikil, a slave, and would therefore be derived from the root meaning “to run,” seen in O. Eng. þraegian, Goth, thagjan, cf. Gr. τρέχειν; Skeat (Etym. Dict., 1898) compares the “trochilus” (Gr. τροχίλος), the small bird that according to Herodotus waits or attends on the crocodile and picks insects out of his teeth.