U00A8

The character U+00A8, commonly known as the diaeresis or umlaut, is a diacritical mark represented by two horizontal dots placed over a letter. It appears in various languages with distinct typographic and linguistic functions. The mark is also occasionally referred to as a trema, particularly in linguistics.

In its role as a diaeresis, the mark indicates that a vowel should be pronounced separately from the preceding vowel, rather than forming a diphthong. For example, in the English word "naïve" or the Spanish "Pingüino," the diaeresis signals distinct syllabic pronunciation. As an umlaut, primarily in Germanic languages, it denotes a sound shift where back vowels (a, o, u) become front vowels (ä, ö, ü), fundamentally altering word meaning and grammar.

The mark appears in numerous languages. German uses it extensively as an umlaut for vowel mutation and pluralization. Spanish employs it to break diphthongs in words like "gue" and "gui" sequences. French utilizes it in words such as "naïf" and "Noël" to separate vowel sounds. It also appears in Dutch, Finnish, and other languages with varying orthographic rules.

From a technical perspective, U+00A8 is the Unicode code point for the spacing diaeresis, a standalone character. The combining version, which attaches to base letters, is U+0308 COMBINING DIAERESIS. In computing, U+00A8 is distinct from precomposed characters like ä (U+00E4) and ü (U+00FC), which integrate the base letter and diacritic into a single code point. The mark originated in medieval scribal practices for indicating vowel separation in Latin manuscripts.