An Etymological Dictionary of the German Language/Annotated/eichen
eichen, aichen, verb, ‘to gauge,’ from Middle High German îchen (ähten), ‘to survey, gauge, inspect’; akin to Middle High German îche, îch, feminine, ‘measure, official standard, office of weights and measures’; corresponds to Dutch ijk, ‘gauge, stamp,’ ijken, ‘to gauge, stamp.’ In Low German and Middle Low German ike, feminine, means ‘gauge mark, instrument for gauging,’ generally ‘a pointed instrument, lance,’ for which reason the cognates have been derived from a Teutonic root îk, ‘to prick.’ Yet Middle High German ähten points to a connection with ahten. In Upper German 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 Old Bavarian ai is also remarkable, since in Suabian and Bavarian ei corresponds to the Middle High German î.