ABSTRACT
The languages of the Celtic group of Indo-European have several features distinguishing them from their geographical neighbours, including (generally) VSO word order, and groups of prepositions taking personal endings. However, the feature that is most often pointed out as peculiar to these languages is mutation, or more precisely initial consonant mutation (in fact, other languages demonstrate this, or a similar, phenomenon, but it is unique among Indo-European languages as a grammaticalized feature).1 This is a feature whereby regular phonological changes occur to the initial consonants of words; however, what makes these changes notable is that they are not triggered by phonological factors (such as preceding phonological environment, or speech rate), but by non-phonological factors, which are of varying types but all basically syntactic (in that it is the position in the sentence that determines whether a word undergoes mutation or not).
