An Etymological Dictionary of the German Language/Annotated/Meineid
Meineid, masculine, ‘false oath, perjury,’ from the equivalent Middle High German meincit, Old High German meincid, masculine; corresponding to Old Saxon mênêth, Dutch meineed, Anglo-Saxon mânâþ, Old Icelandic meineiðr, masculine, ‘perjury.’ It is the common Teutonic word for ‘false oath’; only Gothic *main-aiþs is wanting. The first component is an adjective (or rather an adjective used as a substantive), Middle High German and Old High German mein, ‘false, deceitful,’ as masculine and neuter ‘falsity, injustice, outrage.’ In Middle High German ein meiner was also used for ein meineit; compare Old Saxon mên, Anglo-Saxon mân, masculine, ‘falsity, crime, outrage,’ Old Icelandic mein, neuter ‘damage, injury, misfortune’ (allied to meinn, adjective, ‘hurtful’). Modern High German gemein Gothic gamains) does not seem to be directly akin, although Middle High German mein, ‘outrage,’ may have been the source of the bad sense attached to the modern word. They are, however, finally connected with Slavonic words for Tausch, ‘exchange’ (compare Tausch and. täuschen), Lithuanian maínas, ‘exchange,’ Old Slovenian měna, ‘change, alteration’ (Lettic nút, ‘to exchange’). In that case Latin commûnis and Gothic gamains (see gemein) would mean literally ‘being on a footing cf barter.’ It is probably not related to Latin mentîri.