1st_ Name of the fourth vowel in Spanish . 2nd_ Disjunctive conjunction . 3rd_ 'o' is the symbol of "octet" ( eight bits ). 4th_ 'O' is the chemical symbol of "oxygen". 5th_ 'O' represents to the west at the cardinal points. See W . 6th_ Although it is an error, 'O' is a way to name the type "0" ( zero ) of blood. It is taken from English where it is customary to call the number as the letter.
