O

15th letter of the English alphabet, whose form was derived from the Semitic alphabet. In modern English it represents a wide range of sounds, from the diphthong in ‘so’ to the sounds in ‘or’, ‘lot’, ‘monk’, ‘women’, ‘wolf’, and ‘lemon’.

The North Semitic alphabet, which was the prototype of the Greek, and thus of all the Western alphabets, had no vowel o, as it was a consonantal alphabet. The Greeks adopted the Semitic 'ayin, a symbol representing a pharyngeal fricative that did not exist in Greek. Other symbols were later devised for o, and the Greek alphabet now has the letters omega (Ω, ω) and omicron (Ο, ο).

o

In music, abbreviation for open string, marked over a note in music for a string player; or an indication that a harmonic is to be played (see harmonics).