| Name | Country | Feature class | Latitude | Longitude | |
|---|---|---|---|---|---|
4501  | Ornsay  Ornsay | United Kingdom, Scotland Highland | island | N 57° 9′ 0'' | W 5° 47′ 0'' |
4502  | Ormesby St Margaret Great Ormesby,Ormesby Saint Margaret,Ormesby St Margaret | United Kingdom, England Norfolk > Great Yarmouth District > Ormesby St. Margaret with Scratby | populated place population 2,810 | N 52° 40′ 30'' | E 1° 41′ 18'' |
| 4503 | Ormesby Ormesby | United Kingdom, England Middlesbrough | populated place | N 54° 33′ 0'' | W 1° 11′ 0'' |
| 4504 | Orfordness Orford Ness,Orfordness | United Kingdom, England Suffolk > Suffolk Coastal District > Orford | cape | N 52° 5′ 5'' | E 1° 34′ 38'' |
| 4505 | Orfasay Orfasaj,Orfasay,Orfasy Island,Орфасай | United Kingdom, Scotland Shetland Islands | island | N 60° 29′ 0'' | W 1° 6′ 0'' |
| 4506 | Ore Ora,Ore,oa,オア | United Kingdom, England East Sussex > Hastings District | populated place | N 50° 52′ 13'' | E 0° 36′ 28'' |
| 4507 | Glen Orchy Glen Orchy | United Kingdom, Scotland Argyll and Bute | valley | N 56° 26′ 30'' | W 4° 51′ 9'' |
| 4508 | Orby | United Kingdom, England Lincolnshire > East Lindsey District > Orby | populated place | N 53° 10′ 53'' | E 0° 13′ 55'' |
| 4509 | Openshaw Openshaw,ao peng xiao,奥彭肖,奧彭肖 | United Kingdom, England Manchester | populated place | N 53° 28′ 0'' | W 2° 10′ 0'' |
| 4510 | Onneley Onneley | United Kingdom, England Staffordshire > Newcastle-under-Lyme District > Madeley | populated place | N 52° 59′ 0'' | W 2° 22′ 13'' |
| 4511 | Onich Omhanaich,Onich,Ounich,ao ni he,奥尼赫,奧尼赫 | United Kingdom, Scotland Highland > Inverness-shire | populated place | N 56° 42′ 10'' | W 5° 13′ 30'' |
| 4512 | Onecote | United Kingdom, England Staffordshire > Staffordshire Moorlands > Onecote | populated place | N 53° 5′ 35'' | W 1° 55′ 38'' |
| 4513 | Olton Olton,אולטון | United Kingdom, England Solihull > Bickenhill | populated place | N 52° 26′ 18'' | W 1° 48′ 18'' |
| 4514 | Olney Olney i Buckinghamshire,ao er ni,awlny,أولني,اولنی، باکینگهامشر,奧爾尼 | United Kingdom, England Milton Keynes > Olney | seat of a third-order administrative division population 6,477 | N 52° 9′ 12'' | W 0° 42′ 7'' |
| 4515 | Ollerton Ollerton | United Kingdom, England Nottinghamshire > Newark and Sherwood District > Ollerton and Boughton | populated place | N 53° 13′ 0'' | W 1° 1′ 0'' |
4516  | Loch Ollay Loch Hollay,Loch Ollay | United Kingdom, Scotland Western Isles | lake | N 57° 16′ 0'' | W 7° 22′ 0'' |
| 4517 | Ollach An t-Olach,Ollach | United Kingdom, Scotland Highland | populated place | N 57° 21′ 0'' | W 6° 8′ 0'' |
| 4518 | Ollaberry | United Kingdom, Scotland Shetland Islands | populated place | N 60° 30′ 23'' | W 1° 20′ 14'' |
| 4519 | Old Somerby Old Somerby,Somerby | United Kingdom, England Lincolnshire > South Kesteven District > Old Somerby | populated place | N 52° 53′ 40'' | W 0° 34′ 5'' |
| 4520 | Oldshoremore Aisir Mhor,Oldshore More,Oldshoremore,Àisir Mhòr | United Kingdom, Scotland Highland | populated place | N 58° 28′ 43'' | W 5° 4′ 34'' |
| 4521 | Oldshore Beg | United Kingdom, Scotland Highland | populated place | N 58° 29′ 8'' | W 5° 5′ 54'' |
| 4522 | Old Romney | United Kingdom, England Kent > Shepway District > Old Romney | populated place | N 50° 59′ 24'' | E 0° 53′ 41'' |
| 4523 | Old Rayne Old Rayne,Rayne | United Kingdom, Scotland Aberdeenshire | populated place | N 57° 20′ 38'' | W 2° 32′ 32'' |
| 4524 | Old Radnor | United Kingdom, Wales Powys > Old Radnor | populated place | N 52° 13′ 27'' | W 3° 5′ 59'' |
| 4525 | Old Penshaw Old Penshaw,Painshaw,Penshaw | United Kingdom, England Sunderland | populated place | N 54° 53′ 0'' | W 1° 29′ 0'' |
| 4526 | Old Newton | United Kingdom, England Suffolk > Mid Suffolk District > Old Newton with Dagworth | populated place population 828 | N 52° 13′ 24'' | E 1° 0′ 0'' |
| 4527 | Old Milverton Milverton,Old Milverton | United Kingdom, England Warwickshire > Warwick District > Old Milverton | populated place | N 52° 18′ 15'' | W 1° 34′ 5'' |
| 4528 | Old Man of Hoy Old Man,Old Man of Hoy | United Kingdom, Scotland Orkney Islands | rock | N 58° 53′ 0'' | W 3° 25′ 0'' |
| 4529 | Coniston Old Man Coniston Old Man,Old Man of Coniston,The Old Man of Coniston | United Kingdom, England Cumbria > Westmorland and Furness > Coniston | mountain elevation 802m | N 54° 22′ 13'' | W 3° 7′ 19'' |
| 4530 | Old Malton Old Malton | United Kingdom, England North Yorkshire > Ryedale District > Malton | populated place | N 54° 8′ 42'' | W 0° 46′ 30'' |
| 4531 | Old Hutton Hutton Bridge End,Old Hutton | United Kingdom, England Cumbria > Westmorland and Furness > Old Hutton and Holmescales | populated place | N 54° 17′ 21'' | W 2° 40′ 12'' |
| 4532 | Old Hill Old Hill | United Kingdom, England Sandwell | populated place | N 52° 29′ 0'' | W 2° 4′ 0'' |
| 4533 | Oldhamstocks Oldhamstocks | United Kingdom, Scotland East Lothian | populated place | N 55° 55′ 39'' | W 2° 25′ 5'' |
| 4534 | Old Deer | United Kingdom, Scotland Aberdeenshire | populated place | N 57° 31′ 9'' | W 2° 2′ 15'' |
| 4535 | Old Dalby Old Dalby | United Kingdom, England Leicestershire > Melton District > Broughton and Old Dalby | populated place population 355 | N 52° 48′ 25'' | W 1° 0′ 11'' |
| 4536 | Old Clee Clee,Old Clee | United Kingdom, England North East Lincolnshire | populated place | N 53° 33′ 23'' | W 0° 3′ 11'' |
| 4537 | Oldbury-on-Severn Oldbury,Oldbury upon Severn,Oldbury-on-Severn | United Kingdom, England South Gloucestershire > Oldbury-upon-Severn | populated place population 347 | N 51° 37′ 47'' | W 2° 33′ 56'' |
| 4538 | Oldbury on the Hill Oldbury,Oldbury on the Hill | United Kingdom, England Gloucestershire > Cotswold District > Didmarton | populated place | N 51° 35′ 26'' | W 2° 15′ 50'' |
| 4539 | Old Buckenham | United Kingdom, England Norfolk > Breckland District > Old Buckenham | populated place population 792 | N 52° 28′ 50'' | E 1° 2′ 29'' |
| 4540 | Old Brampton Brampton,Old Brampton | United Kingdom, England Derbyshire > North East Derbyshire > Brampton | populated place | N 53° 14′ 34'' | W 1° 29′ 49'' |
| 4541 | Old Boston | United Kingdom, England St. Helens | populated place | N 53° 28′ 20'' | W 2° 38′ 37'' |
| 4542 | Oldany Island Oldany Island | United Kingdom, Scotland Highland | island | N 58° 15′ 30'' | W 5° 15′ 42'' |
| 4543 | Old Aberdeen Auld Aiberdeen,Old Aberdeen,Seann Obar Dheathain,a bo ding lao cheng qu,オールド・アバディーン,阿伯丁老城区,阿伯丁老城區 | United Kingdom, Scotland Aberdeen City | populated place | N 57° 10′ 1'' | W 2° 6′ 18'' |
| 4544 | Loch Olavat Loch Olavat,Loch Ollevate | United Kingdom, Scotland Western Isles | lake | N 57° 28′ 59'' | W 7° 20′ 13'' |
| 4545 | Beinn an Oir Beinn an Oir | United Kingdom, Scotland Argyll and Bute | peak elevation 785m | N 55° 54′ 6'' | W 6° 0′ 14'' |
| 4546 | Glen Ogle Glen Ogle | United Kingdom, Scotland Stirling | valley | N 56° 24′ 0'' | W 4° 20′ 0'' |
| 4547 | Offord D’Arcy | United Kingdom, England Cambridgeshire > Huntingdonshire > Offord Cluny and Offord D'Arcy | populated place | N 52° 16′ 54'' | W 0° 12′ 52'' |
| 4548 | Offord Cluny Offord,Offord Cluny | United Kingdom, England Cambridgeshire > Huntingdonshire > Offord Cluny and Offord D'Arcy | populated place | N 52° 17′ 19'' | W 0° 12′ 48'' |
| 4549 | Offham | United Kingdom, England Kent > Tonbridge and Malling District > Offham | populated place population 483 | N 51° 17′ 26'' | E 0° 22′ 31'' |
| 4550 | Odstock Odstock | United Kingdom, England Wiltshire > Odstock | populated place | N 51° 2′ 4'' | W 1° 47′ 33'' |
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