Phonological changes from Classical Latin to Proto-Romance

As Classical Latin developed into Proto-Romance it experienced various sound changes. An approximate summary of changes on the phonemic level is provided below. Their precise order is uncertain.

General changes

 * is lost without a trace in all positions.
 * If this results in a collision of identical short vowels, they simply form the corresponding long vowel. Cf. >.


 * Final is lost without a trace in polysyllabic words. Cf.  >.
 * In monosyllables it tends to survive as . Cf. >  > Spanish quién.


 * Clusters consisting of a stop followed by a liquid consonant draw the stress position forward. Cf. >.
 * Two apparent counterexamples are and, judging by the Old French outcomes palpres and poltre.
 * is lost before fricatives, leaving the preceding vowel lengthened (but no longer nasalised). Cf. >.
 * is often retained, or later restored, if it belongs to a prefix (in- or con-) or to a word which has forms where a fricative does not follow . Cf. > French défense, thanks to related forms such as the infinitive  > French défendre.
 * Sequences of two generally merge to a single long . Cf.  >.


 * In some outlying rural areas, the diphthongs and  reduce to  and  respectively in Classical times. Thanks to influence from such dialects, a number of Latin words acquire monophthongized variants early on; cf.  or . Most words, however, remain unaffected by this.
 * Later, 'mainstream' Latin experiences a general monophthongization of to, and of  to , whilst  remains intact in most cases. Cf.  >.


 * turns to the fricative, as does original in intervocalic position or after . Cf.  >.
 * Intervocalic in contact with a rounded vowel tends to disappear. Cf.  >  >.
 * It is often restored if other forms of the word have a non-rounded vowel following . In this case cf. the nominative plural.


 * In hiatus, unstressed front vowels become, while unstressed back vowels become . Cf. >.
 * The same process also affects stressed front and back vowels in hiatus if they are antepenultimate (two syllables from the end of the word). When is produced, primary stress shifts to the following vowel, but when  is produced, primary stress shifts instead to the preceding syllable. Cf.  >.
 * If is formed after a geminate consonant, it is deleted. Cf.  >  >.
 * is deleted before unstressed back vowels. Cf. >  >.
 * is occasionally deleted before unstressed non-back vowels as well. Cf. >  >.
 * Similarly, is delabialized to  before back vowels, whether stressed or not. Cf.  >.
 * If these changes result in sequences of or, these merge to  and  respectively. Cf.  >  >.
 * If forms after, the resulting  simplifies and delabializes to . Cf.  >  >.


 * raises before or . Cf.  >  > Italian cui, fui (not *coi, *foi).
 * before vocalizes to . Cf.  >.


 * Before or after a consonant, and also word-finally, reduces to . Cf.  >.
 * Intervocalically, it sometimes metathesizes to . Cf. >.
 * Words beginning with receive an initial supporting vowel, unless preceded by a word ending in a vowel. Cf.  >.
 * Subsequently, any initial or  before an  cluster is reinterpreted as a supporting vowel and treated accordingly. Cf.  > * > Italian scala, scadere; French échelle, échoir.


 * and before  are raised, respectively, to  and . Cf.  >  > Italian biscia, uscio.
 * Compound verbs stressed on a prefix are usually reconstructed according to their prefixless equivalent, with their stress shifted forward from the prefix. Cf. > *, by analogy with the simplex form.
 * simply yields (rather than *), perhaps because the verb, while recognizable as a compound, was not easy to identify with the original.
 * Some words such as 'fasten' are apparently not recognized as compounds at all and so remain unchanged.
 * Monosyllabic nouns ending in a consonant receive an epenthetic final . Cf. >  >  > French rien.


 * Phonemic vowel length gradually collapses via the following changes (which only affect vowel length, not quality):
 * Long vowels shorten in unstressed syllables.
 * Long vowels shorten in stressed closed syllables.
 * Short vowels lengthen in stressed open syllables.


 * On account of the above, the vowel inventory changes from to, with pre-existing differences in vowel quality achieving phonemic status (and with no distinction between original  and ). Additionally:
 * Unstressed and  merge into  and  respectively.
 * In the second syllable of words with the structure [ˌσσˈσσ], and  merge into  and  respectively.


 * Word-internal 'merges' into a preceding consonant, palatalizing it. Cf.  >  >  > Italian.

Sporadic changes

 * Vowels other than are often syncopated in unstressed word-internal syllables, especially when in contact with liquid consonants or, to a lesser extent, nasal consonants or . Cf.  >.
 * In a few words, unstressed initial syllables followed by experience syncope. Cf.  >.
 * If this results in being followed by a consonant, it may vocalize to . Cf.  >  > * > Italian fòla.
 * If syncope results in, the cluster is generally replaced by . Cf. >.
 * In cases where a long vowel precedes a geminate consonant, one of the elements often shortens unpredictably, sometimes leading to such doublets as >  > Spanish copa, cuba; French coupe, cuve.
 * Long vowels sometimes shorten early on in closed syllables, even if followed by two different consonants, leading to variations such as >  > Italian undici, Spanish once.
 * Conversely, the cluster may lengthen preceding vowels early on. Cf.  >  >.


 * Pretonic vowels sporadically assimilate to, or dissimilate from, the stressed vowel of the following syllable.
 * can dissimilate to before a following . Cf.  >.
 * can dissimilate to before a following . Cf.  >.
 * can dissimilate to before a following . Cf.  >.
 * can dissimilate to before a following back vowel. Cf.  >.
 * can assimilate to a following . Cf. >.
 * can assimilate to a following . Cf. * > *.
 * can assimilate to a following . Cf. > *.


 * and may yield a low-mid vowel if followed by . Cf.  >  > Italian uovo, Sardinian colòra.


 * may yield a mid-vowel if preceded by . Cf. > *.


 * assimilates to a following in a number of cases. Cf.  >.
 * After a long vowel, the resulting reduces to . Cf.  >.
 * Initial and  sometimes voice. Cf.  >.
 * This is particularly frequent with borrowings from Greek. κρυπτή, καμπή > * > Italian grotta, gamba.


 * sometimes assimilates to . Cf. the alternation grundīre~grunnīre.


 * There is occasional loss or assimilation of final, but it is nowhere regular until a much later period.


 * When two neighbouring syllables each contain, one frequently dissimilates to  or is deleted.