Some varieties of Spanish show debuccalization of /s/ to [h] at the end of a syllable, so that a word like estamos "we are" is pronounced [ehˈtamoh].
An example of diachronic lenition can be found in the Romance languages, where the /t/ of Latin patrem ("father", accusative) has become /d/ in Italian and Spanish padre (the latter weakened synchronically /d/ → [ð̞]), while in Catalan pare, French père and Portuguese pai historical /t/ has disappeared completely.
The change of /k/ to [ɡ] in y gath is thus caused by the syntax of the phrase, not by the modern phonological position of the consonant /k/.
Lenition includes the loss of a feature, such as deglottalization, in which glottalization or ejective articulation is lost: [kʼ] or [kˀ] > [k].
Lenition can be seen in Canadian and American English, where /t/ and /d/ soften to a tap [ɾ] (flapping) when not in initial position and followed by an unstressed vowel.
Diachronic lenition is found, for example, in the change from Latin into Spanish, in which the intervocalic voiceless stops [p t k] first changed into their voiced counterparts [b d ɡ], and later into the approximants or fricatives [β̞ ð̞ ɣ̞]: vita > vida, lupa > loba, caeca > ciega, apotheca > bodega.
The subsequent further weakening of the series to phonetic [β̞ ð̞ ɣ̞], as in [loβ̞a] is diachronic in the sense that the developments took place over time and displaced [b, d, g] as the normal pronunciations between vowels.
It is also synchronic in an analysis of [β̞ ð̞ ɣ̞] as allophonic realizations of /b, d, g/: illustrating with /b/, /bino/ 'wine' is pronounced [bino] after pause, but with [β̞] intervocalically, as in [de β̞ino] 'of wine'; likewise, /loba/ → [loβ̞a].
[1] An example of historical lenition in the Germanic languages is evidenced by Latin-English cognates such as pater, tenuis, cornu vs. father, thin, horn.
Although actually a much more profound change encompassing syllable restructuring, simplification of geminate consonants as in the passage from Latin to Spanish such as cuppa > /ˈkopa/ 'cup' is often viewed as a type of lenition (compare geminate-preserving Italian /ˈkɔppa/).
All varieties of Sardinian, with the sole exception of Nuorese, offer an example of sandhi in which the rule of intervocalic lenition applying to the voiced series /b d g/ extends across word boundaries.
[2] A series of synchronic lenitions involving opening, or loss of occlusion, rather than voicing is found for post-vocalic /p t k/ in many Tuscan dialects of Central Italy.
This explains the rise of grammaticalised initial consonant mutations in modern Celtic languages through the loss of endings.
For example:[5] In modern Scottish Gaelic this rule is only productive in the case of dentals but not the other two groups for the vast majority of speakers.
For example, while aon still invokes the rules of blocked lenition, a noun followed by an adjective generally no longer does so.
Outside Celtic, in Spanish orthographic b d g are retained as [b, d, ɡ] following nasals rather than their normal lenited forms [β, ð, ɣ].
In Irish orthography, it is shown by writing the "weak" consonant alongside the (silent) "strong" one: peann, "pen" → ár bpeann "our pen", ceann, "head" → ár gceann "our head" (sonorization is traditionally called "eclipsis" in Irish grammar).
If a language has no obstruents other than voiceless stops, other sounds are encountered, as in Finnish, where the lenited grade is represented by chronemes, approximants, taps or even trills.
For example, Finnish used to have a complete set of spirantization reflexes for /p t k/, though these have been lost in favour of similar-sounding phonemes.
Word-medially, /lː/ is subject to fortition in numerous Romance languages, ranging from [ɖː] or [dː] in many speech types on Italian soil to [dʒ] in some varieties of Spanish.