Diaeresis

dierézis

(separation of one syllable (especially a vowel which is a diphthong) into two distinct syllables)

dierézis

(natural break in rhythm when a word ends at the end of a metrical foot in a line of verse)

tréma

(diacritical mark consisting of two dots (¨) placed over a letter to indicate that it is sounded separately)

umlaut

(diacritical mark consisting of two dots (¨) placed over a letter to indicate that it is sounded separately)