Diaeresis

In typography, a diaeresis (¨) is a diacritical mark used to indicate that two adjacent vowels in a word are pronounced as separate syllables, rather than as a diphthong or a long vowel. The diaeresis is often used to indicate that a vowel is pronounced as a separate syllable, even though it is written as two adjacent vowels. For example, in German, the word "naive" is pronounced "nah-eev" with two separate syllables, rather than as one syllable. The diaeresis is also used in some other languages that have adopted the Latin alphabet, such as French, Dutch, and others.