Edward Sapir developed a theory of linguistic drift which accounted for the irregular change in form and meaning of words. It accounts for the development of holiday from holy day and the meaning dog in a word which originally meant 'hound'. It does not account for the homonymy here, however, since the meanings of the affixal 'homonyms' are precisely regular. Affixes gain and lose particular grammatical functions which themselves seem not to change across languages.