diaeresis
n//daɪˈɛɹəsɪs//dieresis, trema
A separation of one syllable (especially a vowel which is a diphthong, that is, beginning with one sound and ending with another) into two distinct syllables; distraction.
(prosody) A natural break in rhythm when a word ends at the end of a metrical foot in a line of verse.
(orthography) The diacritical mark consisting of two dots (¨) placed over a letter (especially the second of two consecutive vowels) to indicate that it is sounded separately, usually as a distinct syllable.