Entries starting with O
- Occam’s razorOccam's razor is the rule of thumb that when two explanations fit the evidence equally well, you should prefer the one assuming less.
- Old-age dependency ratioThe old-age dependency ratio counts people older than 64 for every 100 people of working age, 15 to 64.
- Oman: Geography, History, Culture and Key FactsOman is a sultanate on the southeastern Arabian Peninsula, bordered by Saudi Arabia, the UAE, and Yemen.
- Orbital eccentricityOrbital eccentricity is a number describing how stretched an orbit is, from 0 for a circle to above 1 for a path that never returns.
- Orthostatic hypotensionOrthostatic hypotension is a drop in blood pressure on standing, of at least 20 mm Hg systolic or 10 mm Hg diastolic within three minutes.
- Osaka: Japan’s Kitchen CityOsaka is a port city on Osaka Bay and the historic commercial and culinary capital of western Japan.
- Oslo: Norway’s Historic CapitalOslo is the capital of Norway, located at the head of the Oslofjord on the country's southeastern coast.
- Ottawa: Canada’s Capital on the Rideau CanalOttawa is the capital of Canada, located on the Ottawa River across from Gatineau, Quebec, and home to the UNESCO-listed Rideau Canal.