o, the fourth of the modern , corresponding to the ʿayin, which represented a breathing and not a vowel. The Semitic form may have derived from an earlier sign representing an .The Greeks in adapting the Semitic alphabet to their own use used this letter (omicron) to express the vowel o, as the letters ʾaleph, he, cheth, and yod were used to express vowels. Vowels were not expressed alphabetically in Semitic. The form of the letter on the Moabite Stone was small o, and this small form appears in early Greek inscriptions from and . In Corinth and in the inscriptions from in Egypt there is a form with an offset dot. A form with a dot in the centre occurs in Thera, and this is paralleled in the large form. At a rounded form similar to an upside-down U occurs. The form, taken from the Chalcidic or Etruscan, was O. The form retains the shape of the letter.The Greeks at first used the letter to represent not only the short closed vowel o but also the long open o and certain other long vowels of the o resulting from contraction or compensatory lengthening. The use of Ω, or omega, in origin apparently a variant form of O with the value of a long vowel, gradually spread with the spread of the throughout the Greek-speaking world. In Latin the letter O stood for the same vowel without distinction of length, and the sound has partly passed into the unchanged, partly with certain alterations, among the more striking of which is the change of short o to ue (e.g., puerto from Latin portum)., O, or o, is the fifteenth letter and the fourth vowel letter of 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 / ˈoʊ / ⓘ), plural oes. [1], Letter O song.This alphabet song will help your children learn letter recognition and the sign language for the letter O. This super-catchy and clear alphabe.