of diaeresis. Greek Ancient Greek In Ancient Greek, synaeresis is the merging and pronunciation of two separate vowels as a diphthong (e.g. α + ι → αι ) or a long vowel (e.g. ο + ο → ου ); a characteristic example of this is the conjugation class or classes of contracted verbs ( – or ). Diaeresis, on the other hand, is the separation of a diphthong into two vowels (αϊ ). Certain words in Proto-Indo-European had two vowels separated by the consonant s or y (esu "good"). In Greek, this consonant changed to h (ehu), and was lost between vowels (eu). In Homer, the two vowels were sometimes pronounced separately (diaeresis: ) and sometimes together (synaeresis: ). Later in Attic Greek, they were always pronounced together. In Greek synaeresis, two vowels merge to form a long version of one of the two vowels (e.g. e + a → ā), a diphthong with a different main vowel (e.g. a + ei → āi), or a new vowel intermediate between the originals (e.g. a + o → ō). Contraction of e + o or o + e leads to ou, and e + e to ei, which are in this case spurious diphthongs. In general, the accent after contraction copies the accent before contraction. Often this means circumflex accent. But for nouns, accent follows the nominative singular. Sometimes this means a different accent from the uncontracted form — i.e., whenever the ending has a long vowel. Contraction in Greek occurs throughout the present and imperfect of contracted verbs and in the future of other verbs. There are three categories based on the vowel of contraction: a, e, or o. Verbs Nouns Contraction also occurs in nouns, including the contracted second declension. S-stem nouns undergo contraction with vowel endings. Some compound nouns show contraction: → "liturgy" Modern Greek In Modern Greek, where original diphthongs are pronounced as monophthongs, synaeresis is the pronunciation of two vowel sounds as a monophthong, and diaeresis is the pronunciation of the two vowels as a diphthong (αϊ ). See also Diaeresis Metaplasm Synalepha Crasis Elision Contraction Synizesis Smoothing (phonetics) Notes and references Notes References Figures of speech Phonetics Poetic devices