| 05.03.02 | Oak leaves |
| 18.11.25 | Oars |
| 06.05.02 | Oases |
| 07.09.04 | Obelisks |
| 27.01.04 | Objects composed of letters or numerals |
| 27.03.05 | Forming letters or numerals |
| 04.07 | Representing a person or animal |
| 26.11.17 | Oblongs |
| 22.01.12 | Oboes |
| 18.07.08 | Ocean liners |
| 26.15.21 | Octagons |
| 03.19.06 | Octopi |
| 15.05 | Office and business machines |
| 07.05.09 | Office interiors |
| 20.01 | Office materials (small) |
| 19.07.21 | Oil cans |
| 07.11.02 | Oil derricks |
| 13.01.03 | Oil lamps |
| 17.07.03 | Oil pressure gauges |
| 19.05.03 | Oil tanks |
| 05.09.06 | Olives |
| 13.01.02 | Olympic torch |
| 08.13.25 | Onion rings |
| 05.11.02 | Onions |
 | Openers |
| 11.01.07 | Bottle |
| 11.05.07 | Can, electric |
| 11.01.07 | Can, non-electric |
| 16.03.05 | Opera glasses |
| 16.03 | Optical apparatus |
| 05.09.03 | Oranges |
| 01.13 | Orbits, astronomic |
| 06.09.04 | Orchards |
| 05.05.06 | Orchids |
| 22.01.01 | Organs (musical) |
| 02.07.08 | Orientals |
| 25 | Ornamental framework |
| 13.01.13 | Ornaments, Christmas |
| 17.07.25 | Oscilloscopes |
| 03.15.13 | Ostriches |
| 12.01.04 | Ottomans |
| 07.01.07 | Outhouses |
| 15.09.03 | Outlets, electrical |
| 26.03 | Ovals |
| 13.03.02 | Ovens and ranges |
| 09.03.02 | Overalls |
| 29.03 | Overlining |
| 03.15.07 | Owls |
| 03.07.01 | Oxen |
| 19.07.23 | Oxygen tanks, portable |
| 03.19.12 | Oysters |
