O

O
O o
Usage
Writing system	Latin script
Type	Alphabetic
Language of origin	Latin language
Phonetic usage	[o] [o̞] [ɔ] [uː] [ʌ] [ɒ] [ø] [a] [ʕ] [w] [◌ʷ] [ʊ] [ə] [ɐ]
Unicode codepoint	U+004F, U+006F
Alphabetical position	15
History
Development	Ο ο 𐌏 O o
Time period	~-700 to present
Descendants	• Ö  • ⱺ  • Ø  • Œ  • Ɔ  • Ơ  • Ỏ  • Ꝋ  • ∅  • º  • ℅
Sisters	ᴥ Ƹ ʿ О Ю Ө ע ع ܥ ࠏ ዐ ࡘ ჺ Ո ո Օ օ ᱳ ᱜ ᱣ
Other
Other letters commonly used with	o(x)
Writing direction	Left-to-Right

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.

History

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 the value in the Old Italic alphabets, including the early Latin alphabet. In Greek, a variation of the form later came to differentiate 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

English

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.

In other contexts, especially before a letter with a minim, ⟨o⟩ may represent the sound , as in 'son' or 'love'. It can also represent the semivowel as in choir or quinoa.

In English, the letter ⟨o⟩ in isolation before a noun, usually capitalized, marks the vocative case, as in the titles to O Canada or O Captain! My Captain! or certain verses of the Bible.

Other languages

⟨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.

Other systems

In the International Phonetic Alphabet, ⟨o⟩ represents the close-mid back rounded vowel.

Related characters

Descendants and related characters in the Latin alphabet

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
  • Ω ω : Greek letter Omega
  • Ο ο : Greek letter Omicron
    • Ⲟ ⲟ : Coptic letter O, which derives from Greek omicron
    • О о : Cyrillic letter O, which also derives from Omicron
    • 𐌏 : Old Italic O, which derives from Greek Omicron, and is the ancestor of modern Latin O
    • Օ օ : Armenian letter O

Computing codes

¹ Also for encodings based on ASCII, including the DOS, Windows, ISO-8859 and Macintosh families of encodings.

Other representations

NATO phonetic	Morse code
Oscar

Signal flag	Flag semaphore	American manual alphabet (ASL fingerspelling)	British manual alphabet (BSL fingerspelling)	Braille dots-135 Unified English Braille

See also

• 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.