Lenition in the context of "Synchronic analysis"

Irish, like all modern Celtic languages, is characterised by its initial consonant mutations. These mutations affect the initial consonant of a word under specific morphological and syntactic conditions. The mutations are an important tool in understanding the relationship between two words and can differentiate various meanings.

Irish, like Scottish Gaelic and Manx, features two initial consonant mutations: lenition (Irish: séimhiú [ˈʃeːvʲuː]) and eclipsis (urú [ˈʊɾˠuː]) (the alternative names, aspiration for lenition and nasalisation for eclipsis, are also used, but those terms are misleading).

In phonetics and phonology, an intervocalic consonant is a consonant that occurs between two vowels. Intervocalic consonants are often associated with lenition, a phonetic process that causes consonants to weaken and eventually disappear entirely. An example of such a change in English is intervocalic alveolar flapping, a process (especially in North American and Australian English) that, impressionistically speaking, replaces /t/ with /d/. For example, "metal" is pronounced [mɛɾl]; "batter" sounds like ['bæ.ɾɚ]. (More precisely, both /t/ and /d/ are pronounced as the alveolar tap [ɾ].) In North American English, the weakening is variable across word boundaries, such that the /t/ of "see you tomorrow" might be pronounced as either [ɾ] or [tʰ]. Some languages have intervocalic-weakening processes fully active word-internally and in connected discourse. For example, in Spanish, /d/ is regularly pronounced like [ð] in the words "todo" [ˈtoðo] (meaning "all") and "la duna [laˈðuna]", meaning "the dune" (but [ˈduna] if the word is pronounced alone).