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|Writing system||Latin script|
|Language of origin||Latin language|
|Time period||~-700 to present|
|Descendants|| • Ö|
|Other letters commonly used with||o(x)|
O, or o, is the 15th letter and the fourth vowel letter in the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is o (pronounced //), plural oes.
Its graphic form has remained fairly constant from Phoenician times until today. The name of the Phoenician letter was ʿeyn, meaning "eye", and indeed its shape originates simply as a drawing of a human eye (possibly inspired by the corresponding Egyptian hieroglyph, cf. Proto-Sinaitic script). Its original sound value was that of a consonant, probably [ʕ], the sound represented by the cognate Arabic letter ع ʿayn.
The use of this Phoenician letter for a vowel sound is due to the early Greek alphabets, which adopted the letter as O "omicron" to represent the vowel /o/. The letter was adopted with this value in the Old Italic alphabets, including the early Latin alphabet. In Greek, a variation of the form later came to distinguish this long sound (Omega, meaning "large O") from the short o (Omicron, meaning "small o"). Greek omicron gave rise to the corresponding Cyrillic letter O and the early Italic letter to runic ᛟ.
Use in writing systems
The letter ⟨o⟩ is the fourth most common letter in the English alphabet. Like the other English vowel letters, it has associated "long" and "short" pronunciations. The "long" ⟨o⟩ as in boat is actually most often a diphthong // (realized dialectically anywhere from [o] to [əʊ]). In English there is also a "short" ⟨o⟩ as in fox, //, which sounds slightly different in different dialects. In most dialects of British English, it is either an open-mid back rounded vowel [ɔ] or an open back rounded vowel [ɒ]; in American English, it is most commonly an unrounded back [ɑ] to a central vowel [a].
Common digraphs include ⟨oo⟩, which represents either // or //; ⟨oi⟩ or ⟨oy⟩, which typically represents the diphthong //, and ⟨ao⟩, ⟨oe⟩, and ⟨ou⟩ which represent a variety of pronunciations depending on context and etymology.
⟨o⟩ is commonly associated with the open-mid back rounded vowel [ɔ], mid back rounded vowel [o̞] or close-mid back rounded vowel [o] in many languages. Other languages use ⟨o⟩ for various values, usually back vowels which are at least partly open. Derived letters such as ⟨ö⟩ and ⟨ø⟩ have been created for the alphabets of some languages to distinguish values that were not present in Latin and Greek, particularly rounded front vowels.
- Œ œ : Latin OE ligature
- O with diacritics: Ø ø Ǿ ǿ Ö ö Ȫ ȫ Ó ó Ò ò Ô ô Ố ố Ồ ồ Ổ ổ Ỗ ỗ Ộ ộ Ǒ ǒ Ő ő Ŏ ŏ Ȏ ȏ Ȯ ȯ Ȱ ȱ Ọ ọ Ɵ ɵ ᶱ Ơ ơ Ớ ớ Ờ ờ Ỡ ỡ Ợ ợ Ở ở Ỏ ỏ Ō ō Ṓ ṓ Ṑ ṑ Õ õ Ȭ ȭ Ṍ ṍ Ṏ ṏ Ǫ ǫ Ȍ ȍ O̩ o̩ Ó̩ ó̩ Ò̩ ò̩ Ǭ ǭ O͍ o͍
- Ꝍ ꝍ : O with loop was used in some medieval Nordic orthographies
- : Old Polish O
- ⱺ : Small o with low ring inside is used in the Swedish Dialect Alphabet
- IPA-specific symbols related to O: ɔ
- IPA superscript letters:
- Uralic Phonetic Alphabet-specific symbols related to O:
- U+1D0F ᴏ LATIN LETTER SMALL CAPITAL O
- U+1D3C ᴼ MODIFIER LETTER CAPITAL O
- U+1D52 ᵒ MODIFIER LETTER SMALL O
- U+1D11 ᴑ LATIN SMALL LETTER SIDEWAYS O
- U+1D13 ᴓ LATIN SMALL LETTER SIDEWAYS O WITH STROKE
- U+1D16 ᴖ LATIN SMALL LETTER TOP HALF O
- U+1D17 ᴗ LATIN SMALL LETTER BOTTOM HALF O
- U+1D54 ᵔ MODIFIER LETTER SMALL TOP HALF O
- U+1D55 ᵕ MODIFIER LETTER SMALL BOTTOM HALF O
- Teuthonista phonetic transcription-specific symbols related to O:
- U+AB3D ꬽ LATIN SMALL LETTER BLACKLETTER O
- U+AB3E ꬾ LATIN SMALL LETTER BLACKLETTER O WITH STROKE
- U+AB3F ꬿ LATIN SMALL LETTER OPEN O WITH STROKE
- U+AB43 ꭃ LATIN SMALL LETTER TURNED O OPEN-O
- U+AB44 ꭄ LATIN SMALL LETTER TURNED O OPEN-O WITH STROKE
- o : Subscript small o is used in Indo-European studies
- : Latin small letter o with retroflex hook is used in phonetic transcription
Derived signs, symbols and abbreviations
- Ꝋ ꝋ : Forms of O were used for medieval scribal abbreviations
- ∅ : empty set symbol
- º : Masculine ordinal indicator
- Calligraphic O (𝒪, 𝓸): Mathematical Alphanumeric Symbols
Ancestors and siblings in other alphabets
- 𐤏 : Semitic letter Ayin, from which the following symbols originally derive
|Unicode name||LATIN CAPITAL LETTER O||LATIN SMALL LETTER O||FULLWIDTH LATIN CAPITAL LETTER O||FULLWIDTH LATIN SMALL LETTER O|
|UTF-8||79||4F||111||6F||239 188 175||EF BC AF||239 189 143||EF BD 8F|
|Numeric character reference||O
- 1 Also for encodings based on ASCII, including the DOS, Windows, ISO-8859 and Macintosh families of encodings.
|NATO phonetic||Morse code|
|Signal flag||Flag semaphore||American manual alphabet (ASL fingerspelling)||British manual alphabet (BSL fingerspelling)||Braille dots-135|
Unified English Braille
- Oxygen, symbol O, a chemical element
- O mark
- Open O (Ɔ ɔ)
- 0 (zero). The capital letter O may be mistaken or misused for the number 0, as they appear quite identical in some typefaces. Early typewriters did not have a 'zero' key: users were actually expected to use capital O.
- "O" Oxford English Dictionary, 2nd edition (1989);Chambers-Happap, "oes" op. cit. Oes is the plural of the name of the letter. The plural of the letter itself is rendered Os, O's, os, o's.
- "Frequency Table". www.math.cornell.edu.
- "Quick search: "o lord"". Retrieved 2013-12-05.
- "IPA Chart with Sounds – International Phonetic Alphabet Sounds". www.internationalphoneticalphabet.org. Retrieved 2023-10-22.
- Constable, Peter (2004-04-19). "L2/04-132 Proposal to add additional phonetic characters to the UCS" (PDF).
- Everson, Michael; Baker, Peter; Emiliano, António; Grammel, Florian; Haugen, Odd Einar; Luft, Diana; Pedro, Susana; Schumacher, Gerd; Stötzner, Andreas (2006-01-30). "L2/06-027: Proposal to add Medievalist characters to the UCS" (PDF).
- Bunčić, Daniel (2021-01-12). "L2/21-039: Proposal to include the letter 'Old Polish O'" (PDF).
- Lemonen, Therese; Ruppel, Klaas; Kolehmainen, Erkki I.; Sandström, Caroline (2006-01-26). "L2/06-036: Proposal to encode characters for Ordbok över Finlands svenska folkmål in the UCS" (PDF).
- Miller, Kirk; Ashby, Michael (2020-11-08). "L2/20-252R: Unicode request for IPA modifier-letters (a), pulmonic" (PDF).
- Everson, Michael; et al. (2002-03-20). "L2/02-141: Uralic Phonetic Alphabet characters for the UCS" (PDF).
- Everson, Michael; Dicklberger, Alois; Pentzlin, Karl; Wandl-Vogt, Eveline (2011-06-02). "L2/11-202: Revised proposal to encode "Teuthonista" phonetic characters in the UCS" (PDF).
- Anderson, Deborah; Everson, Michael (2004-06-07). "L2/04-191: Proposal to encode six Indo-Europeanist phonetic characters in the UCS" (PDF).
- Miller, Kirk (2020-07-11). "L2/20-125R: Unicode request for expected IPA retroflex letters and similar letters with hooks" (PDF).
- Anderson, Deborah (2020-12-07). "L2/21-021: Reference doc numbers for L2/20-266R "Consolidated code chart of proposed phonetic characters" and IPA etc. code point and name changes" (PDF).
- "Earliest Uses of Symbols of Set Theory and Logic". jeff560.tripod.com.
- Media related to O at Wikimedia Commons