- O.⇄O.
an abbreviation for the following:
1. Ocean.
2. Octavo.
3. Ohio.
4. Old.
5. Ontario. - o.⇄o.
an abbreviation for the following:
1. off.
2. officer.
3. order.
4. (Baseball.) outs or putouts (in scoring).
5. (Pharmacy.) pint (Latin, ?octarius or ?octavus).