Meaning

noun a diacritical mark (two dots) placed over a vowel in German to indicate a change in sound

originPIE word *dwís Unadapted borrowing from Late Latin diaeresis (“distribution; division of a diphthong into two syllables”), from Ancient Greek δῐαίρεσῐς (dĭaíresĭs, “distribution, division; division of a poetic line when the end of a word and a metrical foot coincide; division of a diphthong into two syllables”), from δῐαιρέω (dĭairéō, “to divide; to distinguish; to resolve a diphthong or…

Etymology from Wiktionary, CC BY-SA 3.0