Ø

For the similarly named Danish island, see Ø, Denmark.

Øø

The "Ø" (minuscule: "ø"), is a vowel and a letter used in the Danish, Faeroese and Norwegian languages. The vowel is not to be confused with the slashed zero.

Usage

In modern Danish, Faroese, and Norwegian, the letter is a monophthongal close-mid front rounded vowel, the IPA symbol for which is also [ø]. To non-rhotic English speakers, the vowel it sounds most like is the vowel in "bird" or "hurt". Like so many vowels, it has slight variations of the quality called "light" (in Danish søster ("sister") pronounced like eu in French bleu) and "dark" (in Danish "mørke" ("darkness") pronounced similarly to i of English bird); compare light and dark a in English hat and far. (in^[1])
- However, in the Suðuroy-dialect of Faroese short ø is pronounced [ʏ], e.g. børn [bʏdn] (children).

The name of this letter is the same as the sound it represents. Speakers of languages which use the letter ø hold that it is not a ligature or a diacritical variant of the letter o (That is, emically they perceive it as a different letter entirely). Though not its native name, among English-speaking typographers the symbol may be called a "slashed o" or "o with stroke".

The Turkish, Azerbaijani, Turkmen, Tatar, Finnish, Swedish, Icelandic, Rotuman, German, Estonian, and Hungarian alphabets use the letter "Ö" instead of Ø.
In Danish (and Riksmål Norwegian) spelling, ø is also a word and means "island".
Ø is a place in Denmark.
The symbol "ø" is used in the International Phonetic Alphabet to indicate the sound of the Danish and Norwegian letter, the close-mid front rounded vowel.
Although it never appears elsewhere, the letter Ø-with-umlaut is used by the Danish and Swedish national railways in pictograms marking trains crossing the Øresund (da)/Öresund (sv) Bridge between the nations.
There are examples in typesetting of ø being confused with the Greek φ.
The Cyrillic alphabet has "Ө" as the equivalent letter, which are used in the Cyrillic alphabets for Kazakh, Mongolian, Azerbaijani etc.
In linguistics, the capital is used to refer to the linguistic zero.

There are two theories about the origin of the letter ø :-

That it arose as a version of the ligature Œ for a diphthong spelled "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 [ö] sound resulting from i-mutation of [ō]: 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 [ē], but by then use of the letter ø had spread from England to Scandinavia.

For computers, when using the ISO 8859-1 or Unicode sets, the codes for 'Ø' and 'ø' are respectively 216 and 248, or in hexadecimal D8 and F8.
In the TeX typesetting system, the letter is produced by \o
On the Apple Macintosh operating system it can by typed by pressing the [Option] key then typing O or o, while using U.S. keyboard.
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 or 0248 on the numeric keypad, provided the system uses code page 1252 as system default.
The Unicode letter name is "Latin capital/small letter O with stroke".
In HTML character entity references, needed in cases where the letter is not available by ordinary coding, the codes are Ø and ø.
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 default codepage. In Scandinavian codepages, Ø replaces the yen sign (¥) at 165, and ø replaces the ¢ sign at 162.

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. The "∅" symbol is always drawn as a slashed circle, whereas in most typefaces the letter "Ø" is a slashed ellipse. Virtually identical is the diameter sign (Unicode character U+2300).

ØØ Void is an album by the Seattle-based drone doom metal band Sunn O))).
"Ø" is the name of a Finnish experimental Intelligent Dance Music artist, also known as Mika Vainio.
American post hardcore band Underøath uses the ø on some writings of their name, and as a logo to represent themselves.
Bløf is a Dutch pop band.
The Dø is a French Folk-Rock duet.
The 1980s indie band The Bolshoi spelt their name Bølshøi (with one ø reversed for symmetry) on album covers.
Animated band Dethklok is also spelled "Dëthkløk" on some logos.
The British New Wave band Fashiøn always replaced the letter "O" with "Ø" on their records for both the band name and song titles.

In engineering drawings, the symbol ⌀ (closely resembling Ø) preceding a dimension indicates a diameter.
In electrical and electronic engineering, the symbol Φ (Greek letter Phi) , which closely resembles Ø, is called "phase" and designates a phase of alternating current. E.g. - AΦ, BΦ, and CΦ in three phase power or signal circuitry.
In photography, the symbol ⌀ (closely resembling Ø) represents the lens diameter, i.e. a lens with a diameter of 82mm would be written on the lens as: ø 82mm
As an abbreviation for Enhedslisten, a Danish political party
The letter ∅ with two brackets symbolizing a double no set was used as the gang symbol for the Lords of Chaos, a self-styled teen militia. Ex. ( Ø )
In Indonesian car number plates, the symbol ∅ (closely resembling Ø) is placed behind number of registration to distinguish it from number 0. For example: B 2031 ∅T, which is registered in Jakarta.
The ø is used as the o in "The Wørd", a regular segment on The Colbert Report.
A similar symbol was used to mark the name of a gladiator who died in combat in Roman mosaics representing fights.

^ Faqs.org. Danish and Norwegian alphabet contains a recording of a person reciting the Danish alphabet.

Robert Bringhurst (2002). The Elements of Typographic Style, pp. 270, 284. For typographic reference to "slashed o".