An Etymological Dictionary of the German Language/Glocke
Glocke, f., ‘bell, (public) clock,’ from the equiv. MidHG. glocke, OHG. glocka (never chloccha), f.; corresponding to Du. klok, AS. clugge, clucce, E. clock, OIc. klukka, f., ‘bell’; not orig. a G. word, since OHG. chlocchôn, ‘to knock,’ cannot well be allied. The MidLat. clocca recorded in the 8th cent., from which Fr. cloche (in Ital. campana) is derived, is probably due, like the Teut. cognates, to Kelt. origin; comp. W. cloch, f., OIr. cloc, m., ‘bell, clock,’ (primit. Kelt. klukko). It is improbable that the Teut. word is the source of the Rom. and the Kelt. terms, because Teut. itself has usually borrowed the words relating to the Church and its institutions. The OKelt. and Rom. cognates in the form of klukka found their way into Teut.; the HG. forms (Swiss klokke, not χlokχe) may have been first adopted about 800 A.D., from LG. (AS.).