Ø or (minuscule: ø) is a vowel and a letter used in the Danish, Norwegian, Faroese and Southern Sami languages and in the (now dead) language Old Swedish. It is mostly used as a representation of mid front rounded vowels, such as [ø] and [œ], except for Southern Sami where it is used as an [oe] diphthong.
The name of this letter is the same as the sound it represents (see usage). Though not its native name, among English-speaking typographers the symbol may be called a "slashed o" or "o with stroke". Although these names suggest it is a ligature or a diacritical variant of the letter o, it is considered a separate letter in Norwegian and Danish, and it is alphabetized after "z"—thus z, æ, ø, and å.
- In modern Danish, Faroese, and Norwegian, the letter is a monophthongal close-mid front rounded vowel, the IPA symbol for which is also [ø]. As with so many vowels, it has slight variations of "light" quality (in Danish, søster ("sister") is pronounced as [ø], like the "eu" in the French word bleu) and "dark" quality (in Danish, bønne ("bean") is pronounced as [œ], like the "œu" in the French word bœuf). Listen to a Danish speaker reciting the Danish alphabet. In the Suðuroy-dialect of Faroese, the short ø is pronounced [ʏ], e.g. børn [bʏdn] ("children"). The letter was used in both Antiqua and Fraktur from at least as early as the Christian III Bible. Under German influence, the letter ö appeared in older texts (particularly those using Fraktur) and was preferred for use on maps (e.g., for Helsingör or Læsö) until 1957.
- The Southern Sami language uses the letter ø in Norway. It is used in the diphthongs yø [yo] and øø [oe]. In Sweden, the letter ö is preferred.
- Ø is used in the orthographies of several languages of Africa, such as Lendu, spoken in the Democratic Republic of the Congo, and Koonzime, spoken in Cameroon.
- In Danish, ø is also a word, meaning "island". The corresponding word is spelled ö in Swedish and øy in Norwegian.
- Ǿ (Ø with an acute accent) may be used in Danish to distinguish its usage from a similar word with Ø. Example: hunden gǿr, "the dog barks" against hunden gør (det), "the dog does (it)". In Danish, hunden gør, "the dog barks", may sometimes be replaced by the non-authorised spelling hunden gøer. These idiosyncratic spellings are, however, not officially sanctioned. On Danish keyboards and typewriters, the acute accent may be typed above any vowel, by pressing the acute key before pressing the letter, but Ǿ is not implemented in the Microsoft Windows keyboard layout for Danish.
- Ø is used in Old Icelandic texts, when written with the standardized orthography, denoting, among other things the umlauts o > ø and ǫ > ø.
- The Turkish, Azerbaijani, Turkmen, Tatar, Finnish, Swedish, Icelandic, Rotuman, German, Estonian, and Hungarian alphabets use the letter Ö instead of Ø. Hungarian uses Ő for the same sound lengthened.
- Ø/ø is not related to, and should not be confused with, the similar-looking Greek Φ/φ or the Cyrillic Ф/ф.
- The Cyrillic script has Ө as the equivalent letter, which is used in the Cyrillic alphabets for Kazakh, Mongolian, Azerbaijani, etc.
- The letter Ø-with-umlaut (Ø̈, ø̈) was used by the Øresund bridge company, as part of their logotype, to symbolize its union between Sweden and Denmark. Since Ø-with-umlaut did not exist in computer fonts, it was not used in text. The logotype now uses the spelling Øresundsbron, with Øresunds- being Danish and -bron being Swedish. The letter Ø-with-umlaut sometimes appears on packaging meant for the Scandinavian market. For example liquorice brand Snøre/Snöre's logo on the packaging is Snø̈re.
The band Twenty One Pilots also uses the ∅ in their name and in letters that should be an 'O'such as in their abbreviated name tøp or in their own names sometimes.
- The letter "Ø" is sometimes used in mathematics as a replacement for the symbol "∅" (Unicode character U+2205), referring to the empty set as established by Bourbaki, and sometimes in linguistics as a replacement for same symbol used to represent a zero. The "∅" symbol is always drawn as a slashed circle, whereas in most typefaces the letter "Ø" is a slashed ellipse.
- The diameter symbol (⌀) (Unicode character U+2300) is similar to the lowercase letter ø, and in some typefaces it even uses the same glyph, although in many others the glyphs are subtly distinguishable. The diameter symbol is used extensively in engineering drawings, and it is also seen anywhere that abbreviating "diameter" is useful, such as on camera lenses. For example, a lens with a diameter of 82 mm would be labeled ⌀ 82 mm.
- Slashed zero is an alternate glyph for the zero character. Its slash does not extend outside the ellipse (except in handwriting). It is often used to distinguish "zero" ("0") from the Latin script letter "O" anywhere that people wish to preempt confounding of the two, particularly in encoding systems, scientific and engineering applications, computer programming (such as software development), and telecommunications.
- The letter "Ø" is often used in trapped key interlock sequence drawings to denote a key trapped in a lock. A lock without a key is shown as an "O".
- The letter "Ø" is also used in written music, especially Jazz, to type an ad‐hoc chord symbol for a half‐diminished chord, as in "Cø". The typographically correct chord symbol is spelled with the root name, followed by a slashed degree symbol, as in "C𝆩". The slashed degree symbol is found in the musical symbols block of Unicode but is unsupported by some fonts. 𝆩 can always be included with handwriting, however.
There are at least two theories about the origin of the letter ø:
- It possibly arose as a version of the ligature, Œ, of the digraph "oe", with the horizontal line of the "e" written across the "o".
- That it arose in Anglo-Saxon England as an O and an I written in the same place, to represent a long close /ø/ sound resulting from i-mutation of /o/: compare Bede's Northumbrian Anglo-Saxon period spelling Coinualch for standard Cēnwealh (a man's name) (in a text in Latin). Later the letter ø disappeared from Anglo-Saxon as the Anglo-Saxon sound /ø/ changed to /e/, but by then use of the letter ø had spread from England to Scandinavia.
- In OS X, it can be typed by holding O, or o, and then typing 6. In OS X and earlier systems, using a US English-language keyboard, the letter can be typed by holding the [Option] key while typing O, or o, to yield Ø, or ø.
- On an Amiga operating system using any keyboard map, the letter can be typed by holding the [Alt] key while typing O, or o, to yield Ø, or ø.
- On Microsoft Windows, using the "United States-International" keyboard setting, it can be typed by holding down the Alt-Gr key and pressing "L". It can also be typed under any keyboard setting by holding down the Alt key while typing 0216 (for uppercase) or 0248 (for lowercase) on the numeric keypad, provided the system uses code page 1252 as system default. (Code page 1252 is a superset of ISO 8859-1, and 216 and 248 are the decimal equivalents of hexadecimal D8 and F8.)
- Using Microsoft Word, ø and Ø may be typed by pressing Ctrl-/ followed by either minuscule or majuscule O.
- In the X Window System environment, one can produce these characters by pressing Alt-Gr and o or O, or by pressing the Multi key followed with a slash and then o or O.
- In some systems, such as older versions of MS-DOS, the letter Ø is not part of the widely used code page 437. In Scandinavian codepages, Ø replaces the yen sign (¥) at 165, and ø replaces the ¢ sign at 162.
- In Unicode, Ǿ and ǿ have the code points U+01FE and U+01FF. They are not available in the Microsoft Windows keyboard layout for Danish.
Not to be confused with the mathematical signs:
- Robert Bringhurst (2002). The Elements of Typographic Style, pp. 270, 284. For typographic reference to "slashed o".