Celtic Lenition and Western Romance Consonants

‘Lenition’, in German ‘Lenierung’, a term proposed by Rudolf Thurneysen, has nowadays widely superseded the traditional but ambiguous 'aspiration' as the designation of a set of phenomena characteristic of all insular Celtic languages. The least ambiguous definition of 'lenition' is probably that to be found in Thurneysen's Grammar of Old Irish, a revised and enlarged translation of his Handbuch des Altirischen: 'Lenition ... is the term used to describe a mutation of consonants which normally originated in a reduction of the energy employed in their articulation. It affected not only medial, but also such initial consonants as were closely associated with the preceding word. ... It is earlier than the loss of vowels in final and interior syllables ..., for it presupposes the continued existence of these vowels.' In the ensuing paragraphs, Thurneysen indicates the phonetic contexts in which Irish lenition took place; but since we are here concerned with the phenomenon of lenition in general, rather than with the details in any specific form of insular Celtic, we need not list all the situations in the various Goidelic and Brythonic languages in which lenited consonants occur—the less so since we find in attested linguistic stages traces of an extension of the lenited pronunciation to cases where it certainly did not exist at the time when the actual leniting shift originated. Let it suffice here to say that lenition proper arose when a consonant was surrounded by open articulations, mostly vowels and w , but also, in the case of some consonants, when followed by l, r, n . For the sake of simplicity, in what follows we shall frequently use the phrase 'intervocalic position' in reference to all the contexts in which lenition took place.