O, the fourth vowel of the modern alphabet, corresponding to the Semitic ayin, which represented a breathing and not a vowel. The Semitic form may have derived from an earlier sign representing an eye. O (minuscule: 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. There are many systems of example words, including the NATO Phonetic Alphabet, but there are less formal systems as well. For example, Oscar might spell his name on the phone by saying O as in owl, S as in snake, C as in cat, A as in apple, and R as in rabbit. The letter O is the fifteenth letter in the English alphabet and is classified as a vowel. It has two primary sounds: the long O sound, which is like the /O/ in open, and the short O sound, which is like the /o/ in octopus. Did you know? Words Starting With O Browse 9,760 words and phrases that start with the letter O, from oaf to ozotype. This article lists things that start with o across foods, animals, colors, and more. By learning these words, readers can improve their vocabulary and strengthen recall of common categories. Learn the alphabet with Bob the Train in this fun and engaging Letter O Song featuring O for Owl and more! O is used to mean zero, for example when you are telling someone a phone number, or mentioning a year such as 1908. This super-catchy and clear alphabet song also lets children hear the letter O sound and see each letter at the beginning of five simple words paired with colorful kid-friend images. Accents placed on the letter O —such as Ó, Ò, Ô, Õ, and Ö —change pronunciation, meaning, or grammatical emphasis. Accented O has a unique sound, and its usage varies depending on the language and context.