quality:correction, structural:scholar_edition
Lenition

Stop consonants shifted by lenition in Vulgar Latin in some areas.

The voiced labial consonants /b/ and /w/ (represented by ⟨ b ⟩ and ⟨ v ⟩, respectively) both developed a fricative as an intervocalic allophone. This is clear from the orthography; in medieval times, the spelling of a consonantal ⟨ v ⟩ is often used for what had been a ⟨ b ⟩ in Classical Latin, or the two spellings were used interchangeably. In many Romance languages (Italian, French, Portuguese, Romanian, etc.), this fricative later developed into a /v/; but in others (Spanish, Galician, some Catalan and Occitan dialects, etc.) reflexes of /b/ and /w/ simply merged into a single phoneme.

Several other consonants were "softened" in intervocalic position in Western Romance (Spanish, Portuguese, French, Northern Italian), but normally not phonemically in the rest of Italy (except some cases of "elegant" or Ecclesiastical words), nor apparently at all in Romanian. The dividing line between the two sets of dialects is called the La Spezia–Rimini Line and is one of the most important isogloss bundles of the Romance dialects. The changes (instances of diachronic lenition resulting in phonological restructuring) are as follows:Single voiceless plosives became voiced: -p-, -t-, -c- > -b-, -d-, -g-. Subsequently, in some languages they were further weakened, either becoming fricatives or approximants,,, (as in Spanish) or disappearing entirely (such as /t/ and /k/ lost between vowels in French, but /p/ > /v/). The following example shows progressive weakening of original /t/: e.g. vītam > Italian vita, Portuguese vida (European Portuguese), Spanish vida (Southern Peninsular Spanish), and French vie. Some scholars have speculated that these sound changes may be due in part to the influence of Continental Celtic languages, while scholarship of the past few decades has proposed internal motivations.

The sound /h/ was lost but later reintroduced into individual Romance languages. The so-called h aspiré "aspirated h" in French, now completely silent, was a borrowing from Frankish. In Spanish, word-initial /f/ changed to /h/ during its Medieval stage and was lost afterwards (for example farina > harina). Romanian acquired it most likely from the adstrate.

Consonant length is no longer phonemically distinctive in most Romance languages. However some languages of Italy (Italian, Sardinian, Sicilian, and numerous other varieties of central and southern Italy) do have long consonants like /bb/, /dd/, /ɡɡ/, /pp/, /tt/, /kk/, /ll/, /mm/, /nn/, /rr/, /ss/, etc., where the doubling indicates either actual length or, in the case of plosives and affricates, a short hold before the consonant is released, in many cases with distinctive lexical value: e.g. note /ˈnɔte/ (notes) vs. notte /ˈnɔtte/ (night), cade /ˈkade/ (s/he, it falls) vs. cadde /ˈkadde/ (s/he, it fell), caro /ˈkaro/ (dear, expensive) vs. carro /ˈkarro/ (cart, car). They may even occur at the beginning of words in Romanesco, Neapolitan, Sicilian and other southern varieties, and are occasionally indicated in writing, e.g. Sicilian cchiù (more), and ccà (here). In general, the consonants /b/, /ts/, and /dz/ are long at the start of a word, while the archiphoneme |R| is realised as a trill /r/ in the same position. In much of central and southern Italy, the affricates /tʃ/ and /dʒ/ weaken synchronically to fricative and between vowels, while their geminate congeners do not, e.g. cacio /ˈkatʃo/ → (cheese) vs. caccio /ˈkattʃo/ → (I chase). In Italian the geminates /ʃʃ/, /ɲɲ/, and /ʎʎ/ are pronounced as long,, and between vowels, but normally reduced to short following pause: lasciare 'let, leave' or la sciarpa 'the scarf' with, but post-pausal sciarpa with.

A few languages have regained secondary geminate consonants. The double consonants of Piedmontese exist only after stressed /ə/, written ë, and are not etymological: vëdde (Latin vidēre, to see), sëcca (Latin sicca, dry, feminine of sech). In standard Catalan and Occitan, there exists a geminate sound /lː/ written l·l (Catalan) or ll (Occitan), but it is usually pronounced as a simple sound in colloquial (and even some formal) speech in both languages.