O


O
Ⅰ.
O [1] (also o) NOUN (pl. Os or O's) 1) the fifteenth letter of the alphabet. 2) (also oh) zero, especially when spoken). 3) a human blood type (in the ABO system) lacking both the A and B antigens.
Ⅱ.
O [2] SYMBOL the chemical element oxygen.
Ⅲ.
O [3] EXCLAMATION 1) archaic spelling of OH(Cf. ↑oh). 2) used before a name in the vocative.

English terms dictionary. 2015.