An Etymological Dictionary of the German Language/Meineid
Meineid, m., ‘false oath, perjury,’ from the equiv. MidHG. meincit, OHG. meincid, m.; corresponding to OSax. mênêth, Du. meineed, AS. mânâþ, OIc. meineiðr, m., ‘perjury.’ It is the common Teut. word for ‘false oath’; only Goth. *main-aiþs is wanting. The first component is an adj. (or rather an adj. used as a subst.), MidHG. and OHG. mein, ‘false, deceitful,’ as masc. and neut. ‘falsity, injustice, outrage.’ In MidHG. ein meiner was also used for ein meineit; comp. OSax. mên, AS. mân, m., ‘falsity, crime, outrage,’ OIc. mein, n. ‘damage, injury, misfortune’ (allied to meinn, adj., ‘hurtful’). ModHG. gemein Goth. gamains) does not seem to be directly akin, although MidHG. mein, ‘outrage,’ may have been the source of the bad sense attached to the modern word. They are, however, finally connected with Slav. words for Tausch, ‘exchange’ (comp. Tausch and. täuschen), Lith. maínas, ‘exchange,’ OSlov. měna, ‘change, alteration’ (Lett. nút, ‘to exchange’). In that case Lat. commûnis and Goth. gamains (see gemein) would mean lit. ‘being on a footing cf barter.’ It is probably not related to Lat. mentîri.