O's the fifteenth letter of the modern Latin alphabet. Its name in English 's spelled o; the plural's oes, though this's rare. History Egyptian hieroglyph `ir Proto-Semitic O Phoenician O Etruscan O Greek Omicron D4 The letter was derived from the Semitic `Ayin (eye), which represented a consonant, probably the voiced pharyngeal fricative, the sound represented by the Arabic letter ع called `Ayn. This Semitic letter in its original form seems to have been inspired by a si… (More on O)