| Termen/ Term | Nr. apariții/ No. occurrences |
| ONICOFOR | 1 |
| OPAITA | 1 |
| OPAITA ROSIE | 2 |
| OPINTIC | 1 |
| OPINTICA | 1 |
| OPOSUMUL | 5 |
| OPOSUMUL CENUSIU | 1 |
| OPOSUMUL DE APA | 1 |
| ORANGUTAN | 1 |
| ORANGUTANUL | 4 |
| ORASTICA | 2 |
| ORBALT | 1 |
| ORBETE | 18 |
| ORBETELE MARE | 1 |
| ORBETELE MIC | 1 |
| ORESNITA | 3 |
| ORGAN INTERN | 9 |
| ORGAN UMAN | 7 |
| ORGANIZATIA INTERNA | 3 |
| ORGANIZATIA INTERNA LA BROASCA | 1 |
| ORGANIZATIA INTERNA LA BUHAI | 1 |
| ORGANIZATIA INTERNA LA CEGA | 1 |
| ORGANIZATIA INTERNA LA ECHIDNA | 1 |
| ORGANIZATIA INTERNA LA LIPITOARE | 1 |
| ORGANIZATIA INTERNA LA MELC | 1 |
| ORGANIZATIA INTERNA LA PASTRAV | 1 |
| ORGANIZATIA INTERNA LA RAC | 1 |
| ORGANIZATIA INTERNA LA SARPE | 1 |
| ORGANIZATIA INTERNA LA SOPIRLA | 2 |
| ORGANIZATIA INTERNA LA TESTOASA | 1 |
| ORNITORINCUL | 1 |
| ORYX | 1 |
| ORZ PADURET | 1 |
| ORZOAICA | 1 |
| ORZUL SOARECILOR | 6 |
| OS LUNG | 4 |
| OSTRACOD | 28 |
| OSU IEPURELUI | 10 |
| OTARIA NORDICA DE BLANA | 1 |
| OTARIE | 3 |
| OTRATEL | 1 |
| OUA DE PAASRE | 5 |
| OUA DE PASARE | 397 |
| OUA DE RATA MARE | 1 |
| OUA DE RATA ROSIE | 1 |
| OUA DE STIRC ROSU | 3 |
| OVAZ | 1 |
| OVAZ SALBATIC | 1 |