Diaeresis (diacritic)
DIACRITIC OF 2 DOTS OVER A LETTER, USED TO DENOTE THE SEPARATION OF TWO CONSECUTIVE VOWELS
Tréma; Diaraesis; Diareses; Diaeresis mark; Διαίρεσις; Trema (diacritic)
The diaeresis ( ; also known as the trema) and the umlaut () are two different diacritical marks that (in modern usage) look alike. They both consist of two dots placed over a letter, usually a vowel; when that letter is an i or a j, the diacritic replaces the tittle: ï.