One need not go far to find examples of completely unpredictable semantic shifts which would no doubt be rejected as far-fetched were they not verifiable by phonology or historical circumstances. A few English examples will suffice: fascist, based ultimately on Lat. fascis ‘‘bundle (of twigs or straw)’’, which refers to a bundle of rods bound around a projecting axe-head that was carried before an ancient Roman magistrate by an attendant as a symbol of authority and power; fornicate, based on Lat. fornix ‘‘arch’’, where prostitutes lingered in Republican Rome; fiasco ‘‘complete failure’’, based on the Italian word for ‘‘flask’’ in an obscure stage allusion; go ‘‘say’’ (in narrative); and finally bus ‘‘vehicle of mass transportation’’, ultimately the dative plural inflection which remains after the clipping of the Lat. omnibus ‘‘for everyone’’.
Baldi, Philip and B. Richard Page, "Review: Europa Vasconica-Europa Semitica..." Available at: http://www.cls.psu.edu/pubs/pubs/LINGUA1158.pdf