/ əʊ; NAmE oʊ/ noun , exclamation
■ noun (also o ) ( pl. Os , O's , o's / əʊz; NAmE oʊz/)
[ C , U ] the 15th letter of the English alphabet :
'Orange' begins with (an) O / 'O'.
used to mean 'zero' when saying telephone numbers, etc. :
My number is six o double three (= 6033) .
—see also O grade , O level
(especially literary ) = oh