An Etymological Dictionary of the German Language/Annotated/Eidam

by Friedrich Kluge

Eidam, masculine, ‘son-in-law,’ from Middle High German eidem, masculine, ‘son-in-law,’ also ‘father-in-law’ (compare Vetter, Schwager, Base, Neffe, with regard to the fluctuating meaning), Old High German eidum, ‘son-in-law’; corresponds to Anglo-Saxon âðum, Old Frisian âthum, ‘son-in-law.’ Gothic *aiþmus (?) is wanting, the word mêgs (see Mage) being used. This merely West Teutonic term, the derivation of which appears to be similar to that of Oheim, is connected with Middle High German eide, Old High German eidî, Gothic aiþei, ‘mother.’ It is not impossible that it may be allied to Eid also; compare English son-in-law. In Suabian and Alemannian Eidam is unknown, the word used being Tochtermann.