(also o )
■ noun ( plural Os or O's )
1》 the fifteenth letter of the alphabet.
2》 denoting the next after N in a set of items, categories, etc.
3》 a human blood type (in the ABO system) lacking both the A and B antigens.
4》 (also oh ) zero (in a sequence of numerals, especially when spoken).
1》 US Ohio.
2》 Cricket (on scorecards) over(s).
■ symbol the chemical element oxygen.
1》 archaic spelling of oh 1 .
2》 used before a name in the vocative.