o, the fifteenth letter of the english alphabet, derives its form, value, and name from the greek o, through the latin. the letter came into the greek from the ph/nician, which possibly derived it ultimately from the egyptian. etymologically, the letter o is most closely related to a, e, and u; as in e. bone, as. ban; e. stone, as. stan; e. broke, as. brecan to break; e. bore, as. beran to bear; e. dove, as. d/fe; e. toft, tuft; tone, tune; number, f. nombre.-among the ancients, o was a mark of triple time, from the notion that the ternary, or number 3, is the most perfect of numbers, and properly expressed by a circle, the most perfect figure.-the letter o, or its sound.-something shaped like the letter o; a circle or oval.-a cipher; zero.-one.-an exclamation used in calling or directly addressing a person or personified object; also, as an emotional or impassioned exclamation expressing pain, grief, surprise, desire, fear, etc.