dīˈerəsə̇s, esp Brit -ˈi(ə)r- noun
also di·er·e·sis -ˈer-
( plural diaere·ses also diere·ses -əˌsēz)
Etymology: Late Latin diaeresis, from Greek diairesis, from diairein to divide (from dia- + hairein to take) + -sis — more at heresy
1. : the resolution of one syllable into two especially by separating the vowel elements of a diphthong or by resolving a w or y sound into a vowel — opposed to syneresis
2. : the mark ¨ placed over a vowel (as over the second of two adjacent vowels) to indicate that the vowel is pronounced in a separate syllable (as in naïve, Boëthius, Brontë ) — compare umlaut
3. prosody : the break caused by the coincidence of the end of a foot with the end of a word — distinguished from caesura
4. : division 15