The name of this letter is the same as the sound it represents (seeusage). Among English-speaking typographers the symbol may be called a "slashed O"[1] or "o with stroke". Although these names suggest it is aligature or adiacritical variant of the letter⟨o⟩, it is considered a separate letter in Danish and Norwegian, and it is alphabetized after⟨z⟩ — thus⟨x⟩,⟨y⟩,⟨z⟩,⟨æ⟩,⟨ø⟩, and⟨å⟩.
In other languages that do not have the letter as part of the regular alphabet, or in limitedcharacter sets such asASCII,⟨ø⟩ may correctly be replaced with thedigraph⟨oe⟩, although in practice it is often replaced with just⟨o⟩, e.g. inemail addresses. It is equivalent to⟨ö⟩ used in Swedish (and a number of other languages), and may also be replaced with⟨ö⟩, as was often the case with older typewriters inDenmark andNorway, and in national extensions ofInternational Morse Code.[citation needed]
In modernDanish,Faroese, andNorwegian, the letter generally representsclose-mid front rounded vowel, theIPA symbol for which is[ø] (Unicode U+00F8). As with so many vowels, it has slight variations in quality. Besides the close-mid vowel, as in Danishsøster ("sister") pronounced[ø], like the⟨eu⟩ in the French wordbleu),⟨ø⟩ may have a lower vowel quality, e.g. in Danishbønne ("bean") pronounced[œ], like the⟨œu⟩ in the French wordbœuf).[2] In theSuðuroy-dialect of Faroese, the short⟨ø⟩ is pronounced[ʏ], e.g.børn[bʏdn] ("children"). The letter was used in bothAntiqua andFraktur from at least as early as theChristian III Bible. Under German influence, the letterö appeared in older texts (particularly those usingFraktur) and was preferred for use on maps (e.g., forHelsingör orLæsö) until 1957.[3]
TheSouthern 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.
Ǿ (Ø with anacute accent,Unicode U+01FE) may be used inDanish on rare occasions to distinguish its use from a similar word with Ø. Example:hunden gǿr, "the dog barks" againsthunden gør (det), "the dog does (it)". This distinction is not mandatory and the first example can be written eithergǿr orgør; the first variant (with ǿ) would only be used to avoid confusion. The second example cannot be spelledgǿr. In Danish,hunden gør, "the dog barks", may sometimes be replaced by the non-standard spellinghunden gøer. This is, however, usually based on a misunderstanding of the grammatic rules ofconjugation of verbs ending in the letters ø andå. These idiosyncratic spellings are not accepted in the official language standard. 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 inOld Icelandic texts, when written with the standardized orthography, denoting, among other things theumlautso > ø andǫ > ø.
Ø (or more properly, the similarnull sign, ∅), is used in English as a short for "no" or "none", but this usage is discouraged in handwriting, since it may be mistaken as another number, especially "0".[5]
Ø / ø is not related to, and should not be confused with similar-lookingGreek Φ /φ orCyrillicФ / ф.
TheCyrillic letterӨ has the same sound as Ø, which is used in the Cyrillic alphabets forKazakh,Mongolian,Azerbaijani, and other languages that have this sound. This is not to be confused with theEarly Cyrillic letterfita Ѳ.
The letter Ø-with-diæresis (Ø̈, ø̈) was used by theØresund bridge company, as part of theirlogotype, to symbolize its union between Sweden and Denmark. Since Ø-with-diæresis did not exist in computer fonts, it was not used in the text. The logotype now uses the spelling Øresundsbron, with Øresunds- being Danish and -bron being Swedish. The letter Ø-with-diæresis sometimes appears on packaging meant for the Scandinavian market so as to prevent printing the same word twice. For example,liquorice brand Snøre/Snöre's logo on the packaging isSnø̈re. The letter is rarely used on maps (e.g.: Malmø̈).[6]
InOld Polish texts, the letter Ꟁ / ꟁ, called "o rogate" (eng. "horned o"), represented a nasal vowel (after all nasal vowels had merged, but before they re-diverged in modern Polish). Due to limitations in printing technology, this letter has sometimes been rendered asø,φ, orϕ.
The letter "Ø" is sometimes used in mathematics as a replacement for the symbol "∅" (Unicode character U+2205), referring to theempty set as established byBourbaki, and sometimes in linguistics as a replacement for same symbol used to represent azero. The "∅" symbol is always drawn as a slashedcircle, whereas in most typefaces the letter "Ø" is a slashedellipse.
Thediameter symbol (⌀) (Unicode character U+2300) is similar to the lowercase letter ø, and in sometypefaces it even uses the sameglyph, although in many others the glyphs are subtly distinguishable (normally, the diameter symbol uses an exact circle and the lettero is somewhat stylized). The diameter symbol is used extensively inengineering drawings, and it is also seen in situations where abbreviating "diameter" is useful, such as oncamera lenses. For example, a lens with a diameter of 82 millimeters would be engraved with" ⌀ 82 mm ".
Ø or⌀ is sometimes also used as a symbol foraverage value, particularly in German-speaking countries. ("Average" in German isDurchschnitt, directly translated ascut-through.)[7]
Slashed zero is an alternateglyph for thezero character. Its slash does not extend outside the ellipse (except in handwriting). It is often used to distinguish "zero" ("0") from theLatin script letter "O" anywhere that people wish to preemptconfounding of the two, particularly inencoding systems, scientific and engineering applications,computer programming (such assoftware development), and telecommunications. It is also used in Amateur Radio call signs, such as XXØXX, XØXXX, and so on, in the United States and in other countries. See, also,[8] for information on international amateur radio call signs.
The letter "Ø" is often used intrapped-key interlock sequence drawings to denote a key trapped in a lock. A lock without a key is shown as an "O".
The letter arose as a version of theligature⟨oe⟩. In Danish manuscripts from the 12th and 13th century, the letter used to represent an/ø/ sound is most frequently written as an⟨o⟩ with a line through, but also⟨oe⟩. The line could both be horizontal or vertical.[9]
Danish keyboard with keys for Æ, Ø, and Å. On Norwegian keyboards theÆ and Ø switch places.
Some 7-bit ASCII variants defined byISO/IEC 646 use0x5C for Ø and0x7C for ø, replacing the backslash and vertical bar.The most common locations inEBCDIC code pages is0x80 and0x70.Most code pages used byMS-DOS such asCP437 did not contain this character; in Scandinavian codepages, Ø replaces theyen sign (¥) at 165, and ø replaces the¢ sign at 162.The 8-bitISO-8859-1 and similar sets used0xD8 and0xF8; these locations were then inherited byCP1252 on Windows, and byUnicode.
U+00D8ØLATIN CAPITAL LETTER O WITH STROKE (Ø)
U+00F8øLATIN SMALL LETTER O WITH STROKE (ø)
Not to be confused with the mathematical signs:
U+2205∅EMPTY SET (∅, ∅, ∅, ∅)
^Muntzel, Martha; Martínez, Aileen (2014)."El Alfabeto Práctico Pjyɇkakjo".Estudios de Cultura Otopame.9. Universidad Nacional Autónoma de México Instituto de Investigaciones Antropológicas. Retrieved3 November 2025.
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