The New Student's Reference Work/O

O, the fifteenth letter, is a vowel, and represents seven sounds.  It is produced through the rounded lips, and is therefore classified as the labial vowel.  Its principal sounds are the long one in bone and the short one in nod.  Variants of these are heard in orb, son, do (food) and wolf (book).  With other vowels it forms diagraphs and diphthongs.  Anciently it was a numeral (11) as well as a letter, O with a bar over it being 11,000.  O’ with an apostrophe after it in Irish names is a prefix meaning son of as O’Connell, son of Connell.