o

o UK [əʊ] / US [oʊ] or O UK / US noun
Word forms "o":
singular o plural o's
Word forms "O":
singular O plural O's

1) [countable/uncountable] the 15th letter of the English alphabet. O is a vowel.

2) [countable/uncountable] spoken a way of saying "zero", used for example when you are telling someone a telephone number or saying a date such as 1904

3) [uncountable] medical a common blood group in the ABO system

•

See:

O I