sort by Rank | Alpha
| Possible Meanings | Rank |
| of homeland security | **** |
| Oak Hall School | **** |
| Of Occupational Health and Safety | **** |
| Ovonic Hydrogen Systems | **** |
| Orlando High School | **** |
| Occupational Health Standard | **** |
| Oysterponds Historical Society | **** |
| Occupation Health and Safety | **** |
| Oral Health Section | **** |
| Omak High School | **** |
| Ozaukee Humane Society | **** |
| Occupational Health Services | **** |
| Organisations Health and Safety | **** |
| Oregon Humane Society | **** |
| Orchestra the Symphony | **** |
| October Household Survey | **** |
| Occupational Hygiene Services | **** |
| Occupational Health Survey | **** |
| Oxford Historical Society | **** |
| Open Hypermedia Systems | **** |
| Oasis High School | **** |
| Ogden High School | **** |
| Operation Head Start | **** |
| Othello High School | **** |
| Occupational Health Service | *** |
| Oromocto High School | *** |
| Occupational Health Schemes | *** |
| Open Hypertext Systems | *** |
| Online Hiring System | *** |
| Office of Housing Services | *** |
| Organizational Health Survey | *** |
| Of the Ohio Historical Society | *** |
| Oregon Human Services | *** |
| Oklahoma Horseshoeing School | *** |
| Orchard Hardware Supply | *** |
| Optimum Health Services | *** |
| Organization of Human Services | *** |
| Oregon Health Services | *** |
| Of Health Sciences | *** |
| Occupational Health and Security | *** |
| Omnibus Household Survey | *** |
| Ovarian Hyperstimulation Syndrome | *** |
| Oklahoma Honor Society | *** |
| Old House Society | *** |
| Ooltewah High School (Ooltewah, TN) | *** |
| Open Hyperdocument Systems | *** |
| Old Hammondtown School | *** |
| Oneonta Historical Society | *** |
| Offener Hamburger Schulserver | *** |
| Omaha Healthy Start | *** |
| Ontario Handweavers Spinners | *** |
| Ornamental Hinge Strap | *** |
| Oklahoma Horticultural Society | *** |
| Ontario Herpetological Society | *** |
| Our High School | *** |
| Oxford Handicap Scale | *** |
| Organisational Health Survey | *** |
| Organizational Health Safety | *** |
| Ossipee Historical Society | *** |
| ORAL HEALTH SERVICES | *** |
| Ontario Handweavers and Spinners | *** |
| Ontario Herpetofaunal Summary | *** |
| Oregon Health Sciences | *** |
| Oral History Society | *** |
| Oregon Herpetological Society | *** |
| Of HIPAA Standards | *** |
| Open High School | *** |
| Oak Hollow Stable | *** |
| Over Head System | *** |
| Olathe Historical Society | *** |
| Oral Health Sciences | *** |
| Ogburn Home School | *** |
| Optimal Hardware Solutions | *** |
| Oberlin Historical Society | *** |
| Oakmont High School | *** |
| Office of Health Statistics | *** |
| Occupied Heating Setpoint | *** |
| Orono High School | ** |
| Office of HIPAA Standards | ** |
| Office of Hazardous | ** |
| obesitas-hypoventilation syndrome | ** |
| objective health status | ** |
| Occupational Hazards Survey | ** |
| Occupational Health Supplement | ** |
| occupational healthcare services | ** |
| Occupational Hygiene Survey | ** |
| Ocular Histoplasmosis Study | ** |
| oral hydration solution | ** |
| oral hydration solutions | ** |
| Oral Hygiene Study | ** |
| out-hospital subsample | ** |
| Occupational Health Strategy | ** |
| Offshore Handling Systems | ** |
| Olean High School | ** |
| Oil and Hazardous Substance | ** |
| Office of Homeless Services | ** |
| Otsu Hydrobiological Station | ** |
| Office of Human Services | ** |
| Ontario Humane Society | ** |
| Ontario Health Status Survey | ** |
| Oxford hip score | ** |
| Optical Hubbing Service | ** |
| Open Hearth Steel | ** |
| Office for Homeland Security | ** |
| Oxbow High School | ** |
| Observation Handling Subsystem | ** |
| Optometric Historical Society | ** |
| Ozona High School | ** |
| Ontario Hydro Services | ** |
| Office of Health Sciences | ** |
| Oral Heath Science | ** |
| Optimum Hospice Solutions | ** |
| Occupation Health Safety | ** |
| Otolaryngology Historical Society | ** |
| Outboard Horizontal Stabilizer | ** |
| Open Hydroponics System | ** |
| Opposite Heel Strike | ** |
| Open Hyermedia Systems | ** |
| Owosso High School | ** |
| Ozaukee Humane Societies | ** |
| Overbrook High School | ** |
| Occu Health Safety | ** |
| Oakwood Healthcare System | ** |
| Oil or Hazardous Substance | ** |
| Occupations Health Systems | * |
| Ohlone Humane Society | * |
| Oil and Hazardous Substances | * |
| offshore handling services | * |
| Omaha Hearing School | * |
| Online Help Ship | * |
| Ozark Humane Society | * |
| Occupational Health Site | * |
| Ohio Hydraulic Service | * |
| Ongoing Home Survey | * |
| Ordnance Hoist System | * |
| Occupational Hygiene Solutions | * |
| Open Hypertext System | * |
| Overhead Hoist Shuttle | * |
| Occupational Health Subsequent | * |
| Orkney Heritage Society | * |
| Oil Hazardous Substances | * |
| Oakland Health Start | * |
| Off Highway vehicles in Surface | * |
| Office of Hearing Services | * |
| Office of the Head of State | * |
| Online Help Storefront | * |
| Online Hockey Statistics | * |
| Original Hammock Shop | * |
| Oulu Health Sciences | * |