A diaeresis is a pair of dots that appear over a vowel to indicate that the vowel is pronounced separately from an adjacent vowel. Its first use, though, was to separate a vowel at the start of a new word from a vowel at the end of a preceding word, because Greek was originally written without any spaces between words. The term umlaut, which comes from a German word roughly meaning ‘sound change’, is also used in Germanic linguistics to refer to certain kinds of vowel changes, especially when a vowel moves closer to /i/.