An Etymological Dictionary of the German Language/eichen
eichen, aichen, vb., ‘to gauge,’ from MidHG. îchen (ähten), ‘to survey, gauge, inspect’; akin to MidHG. îche, îch, f., ‘measure, official standard, office of weights and measures’; corresponds to Du. ijk, ‘gauge, stamp,’ ijken, ‘to gauge, stamp.’ In LG. and MidLG. ike, f., means ‘gauge mark, instrument for gauging,’ generally ‘a pointed instrument, lance,’ for which reason the cognates have been derived from a Teut. root îk, ‘to prick.’ Yet MidHG. ähten points to a connection with ahten. In UpG. pfechten (see Pegel) has a parallel form pfechen. The solution of the difficulty with regard to aichen has not yet been found. The spelling of the word with OBav. ai is also remarkable, since in Suab. and Bav. ei corresponds to the MidHG. î.