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. Its original sound value was that of a consonant, probably, the sound is 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. 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 from the short o. Greek omicron gave rise to the corresponding Cyrillic letter O and the early Italic letter to runic ᛟ. Even alphabets that are not derived from Semitic tend to have similar forms to represent this sound; for example, the creators of the Afaka and Ol Chiki scripts, each invented in different parts of the world in the last century, both attributed their vowels for 'O' to the shape of the mouth when making this sound.
The letter 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" as in boat is actually most often a diphthong . In English there is also a "short" 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 or an open back rounded vowel ; in American English, it is most commonly an unrounded back to a central vowel. Common digraphs include, which represents either or ; or, which typically represents the diphthong, and,, and which represent a variety of pronunciations depending on context and etymology. In other contexts, especially before a letter with a minim, may represent the sound, as in 'son' or 'love'. It can also represent the semivowel as in choir or quinoa. In English, the letter 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
is commonly associated with the open-mid back rounded vowel, mid back rounded vowel or close-mid back rounded vowel in many languages. Other languages use for various values, usually back vowels which are at least partly open. Derived letters such as and have been created for the alphabets of some languages to distinguish values that were not present in Latin and Greek, particularly rounded front vowels.
