sort by Rank | Alpha
| Possible Meanings | Rank |
| Orthodontic Centers of America | **** |
| Ontario Clean Air Alliance | *** |
| Ontario College Athletic Association | *** |
| Oregon Commission on Asian Affairs | *** |
| ovarian cystadenocarcinoma-associated antigen | ** |
| ovarian cystadenocarcinoma-associated antigens | ** |
| Other Changes in Assets Account | ** |
| Oklahoma City Ada Atoka | ** |
| Ontario Crown Attorneys Association | ** |
| Orange County AmeriCorps Alliance | ** |
| Ontario Commerical Arborists Assocation | ** |
| Ontario Colleges Athletics Association | ** |
| Oldham County Arts Association | ** |
| Otsego County Arts Alliance | ** |
| Ontario College Athletics Association | ** |
| Okanagan College Alumni Association | ** |
| Orange County Astronomical Association | ** |
| Office of Administration ADM | * |
| Office of Compliance and Affirmative Action | * |
| Orange County Aviation Association | * |
| Onset Creative Arts Association | * |
| Oregon Casualty Adjusters Association | * |
| Orthodox Christian Alumni Association | * |
| Onondaga Council on Alcoholism and Addictions | * |
| Ouray County Arts Association | * |
| Orange County Alarm Association | * |
| Ovarian Cystadenocarcinoma Associated Antigen | * |
| Office of Commission Appellate Adjudication | * |