O
Short entries beginning with O that only one encyclopedia carries are gathered on page 1 page 2 page 3 page 4 page 5 page 6 page 7 page 8 page 9 page 10 page 11 page 12 page 13 page 14 page 15 page 16 page 17 page 18 page 19 page 20 page 21 page 22 page 23 page 24 page 25 page 26 page 27 page 28 page 29 page 30 page 31 page 32 page 33 page 34 page 35 page 36 page 37 page 38 page 39.
- O'Connell
- O'Connell, Daniel
- O'Gorman (THOMAS an American clergyman)
- O'Hara, Theodore
- Oak 2 sources
- Oak Tree
- Oates 2 sources
- Oath 2 sources
- Oats
- Obelisk 2 sources
- Obercit, Johnan Hermann
- Observatory 2 sources
- Obsession and Possession
- Occupational
- Ocean
- Octopus
- Octroi 2 sources
- Odessa 2 sources
- Odin
- Odoacer 2 sources
- Odyle (also Od, Odic Force, Odyllic Force)
- Oedenburg
- Oedipus 2 sources
- Offenbach
- Oglethorpe, James Edward
- Ohio
- Ohio (State in the North Central)
- Oil
- Oil Pipe Lines
- Oils and Fats
- Oklahoma
- Oklahoma (State in the South Central)
- Oklahoma City
- Olcott, Colonel Henry Steel
- Old Age
- Old Age Pensions 2 sources
- Oleomargarine 2 sources
- Olive
- Oliver
- Olmsted (IV)
- Olmsted, Frederick Law
- Olympia
- Olympiad
- Olympic Games
- Omaha
- Omaha
- Omar Khayyam 3 sources
- Onion 2 sources
- Ontario
- Ontario (LAKE live stock sold)
- Ontario (LAKE the smallest and most E)
- Ontario (Province of the Dominion)
- Onyx 4 sources
- Opal 4 sources
- Open-hearth Cast Steel
- Open-sand Moulding
- Opera 2 sources
- Opium
- Oporto 2 sources
- Opossum
- Optative
- Optography
- Oracles
- Orang Outang
- Orange
- Orange Free State Province
- Orange-Utan
- Orangemen
- Oratorio
- Orchestra
- Orchids
- Orchomenos
- Ordeal 2 sources
- Order
- Orders
- Ordination
- Ore
- Oreads
- Oregon
- Oregon
- Oreide
- Orestes 3 sources
- Organ
- Organ
- Orinoco 2 sources
- Oriole 2 sources
- Orion 2 sources
- Orkney Islands 2 sources
- Ormolu 2 sources
- Ormonde
- Ornaments
- Orpheus 3 sources
- Orton 2 sources
- Osaka 2 sources
- Oscans
- Osiris 3 sources
- Ossoli 2 sources
- Osteopathy 2 sources
- Ostia 2 sources
- Ostracism 2 sources
- Ostrich
- Othman
- Otho
- Otis
- Otis, James
- Ottawa (City of Ontario Canada)
- Ounce
- Ouzel 2 sources
- Ovid 2 sources
- Owen, Robert
- Owl
- Oxford 2 sources
- Oxidizing Silver
- Oxygen
- Oxygen 2 sources
- Oyster 2 sources
- Ozone