| OPSA | OPSA (disambiguation) | Opsada |
| Opsada (1956) | Opsada Sarajeva | Opsada sarajeva |
| Opsahl | Opsahl Commission | OpSail |
| Opsail | Opsal, Frank | Opsangervatnet |
| Opsanus | Opsanus beta | Opsanus tau |
| Opsanus vandeuseni | Opsaridium | Opsaridium boweni |
| Opsaridium engrauloides | Opsaridium leleupi | Opsaridium loveridgii |
| Opsaridium maculicauda | Opsaridium microcephalum | Opsaridium microlepis |
| Opsaridium peringueyi | Opsaridium splendens | Opsaridium tweddleorum |
| Opsaridium ubangiense | Opsaridium zambezense | Opsariichthys |
| Opsariichthys bea | Opsariichthys bidens | Opsariichthys dienbienensis |
| Opsariichthys duchuunguyeni | Opsariichthys elegans | Opsariichthys evolans |
| Opsariichthys hainanensis | Opsariichthys hieni | Opsariichthys kaopingensis |
| Opsariichthys minutus | Opsariichthys pachycephalus | Opsariichthys songmaensis |
| Opsariichthys steenackeri | Opsariichthys uncirostris | Opsarius |
| Opsarius barna | Opsarius barnoides | Opsarius bernatziki |
| Opsarius cocsa | Opsarius koratensis | Opsarius maculatus |
| Opsarius nelsoni | Opsarius pulchellus | Opsarius tileo |
| Opsaroa | Opsaroa fulvinota | OPSB |
| OPSBI | OPSCC | Opsci |
| Opscode | OPSD | OPSEC |
| Opsec | OpSec | OPSEK |
| Opsenica | Opseogymnus | Opseth |
| OPSEU | Opsherin | Opshop |
| OpShop | Opshtina | OPSI |
| Opsi | OPSI (disambiguation) | Opsi (open pc server integration) |
| Opsia Araba | Opsia gens | Opsiandra |
| Opsibidion | Opsibidion albifasciatum | Opsibidion albinum |
| Opsibidion flavocinctum | Opsibotys | Opsibotys benenotata |
| Opsibotys flavidecoralis | Opsibotys fuscalis | Opsibotys hasanensis |
| Opsibotys latipennis | Opsibotys ocellalis | Opsibotys profusalis |
| Opsicarpium | Opsicarpium insignis | Opsician |
| Opsician Theme | Opsician theme | Opsicians |
| Opsicion | Opsiclines | Opsiclines leucomorpha |
| Opsida Sigecka | Opsida sigecka | Opsidia gens |
| Opsidiscidae | Opsieobuthus | Opsieobuthus tungeri |
| Opsies | Opsies capra | Opsigalea |
| Opsigalea blanchardi | Opsiini | Opsikion |
| Opsikion theme | Opsilia | Opsilia aspericollis |
| Opsilia badenkoi | Opsilia bucharica | Opsilia chinensis |
| Opsilia coerulescens | Opsilia gens | Opsilia irakensis |
| Opsilia longitarsis | Opsilia malachitica | Opsilia molybdaena |
| Opsilia prasina | Opsilia schurmanni | Opsilia transcaspica |
| Opsilia uncinata | Opsilia varentzovi | Opsilia virescens |
| Opsimath | Opsimaths | Opsimathy |
| Opsimini | Opsimus | Opsimus quadrilineatus |
| Opsin | Opsin 4 | Opsin kinase |
| Opsin kinase (phosphorylating) | Opsine | Opsins |
| Opsioleus adversus | Opsiomyia | Opsiphanes |
| Opsiphanes blythekitzmillerae | Opsiphanes cassiae | Opsiphanes cassina |
| Opsiphanes sallei | Opsiphanes singularis | Opsiplanon |
| Opsiplanon luellus | Opsirhina | Opsirhina albigutta |
| Opsirhina lechriodes | Opsirhina metallescens | Opsirhina metaphaea |
| Opsirhina tintinarra | Opsis | Opsismodysplasia |
| Opsistylis | Opsite | OpSite |
| Opsites | Opsites of Lazica | Opsithrissops |
| Opsitycha squalidella | Opsius | Opsius stactogalus |
| Opsječko | Opsjecko | Opsk |
| OPSK | OPSkins | OPSM |
| OPSN | Opsoclonic cerebellopathy | Opsoclonus |
| Opsoclonus Myoclonus | Opsoclonus myoclonus | Opsoclonus Myoclonus Ataxia |
| Opsoclonus myoclonus ataxia | Opsoclonus myoclonus syndrome | Opsoclonus Myoclonus syndrome |
| Opsoclonus-myoclonus syndrome | Opsodoca | Opsodoras |
| Opsodoras steindachneri | Opsodoras stuebelii | Opsoempheria |
| Opsoleskia | Opsomantis | Opsomeigenia |
| Opsommer, Paul | Opsomyoclonus | Opson |
| Opsona Therapeutics | Opsonin | Opsonin proteins |
| Opsonins | Opsonisation | Opsonization |
| Opsonize | Opsonized | Opsonizer |
| Opsophagos | Opsophagus | Opsophagus nigripalpis |
| Opsophagus ornatus | Opsophasiopteryx | Opsopoeodus |
| Opsopoeodus bollmani | Opsopoeodus emiliae | Opsosturmia |
| Opsotheresia | Opsotheresia bigelowi | Opsotheresia nigricornis |
| Opsotheresia obesa | Opsound | OpSource |
| Opsozelia | OPSR | OPSS |
| OPSS (disambiguation) | Opst | OPST |
| Opstad | Opstad Forced Labor Institution | Opstad, Mark |
| Opstead, Minnesota | Opsterland | Opstibranchia |
| Opstina | Opstina Ada | Opstina Alibunar |
| Opstina Apatin | Opstina Aracinovo | Opstina Aracinovo, Republic of Macedonia |
| Opstina Bac | Opstina Bac, Republic of Macedonia | Opstina Backa Palanka |
| Opstina Backa Topola | Opstina Backi Petrovac | Opstina Barajevo |
| Opstina Becej | Opstina Bela Crkva | Opstina Belcista |
| Opstina Belcista, Republic of Macedonia | Opstina Bistrica | Opstina Bogdanci |
| Opstina Bogdanci, Republic of Macedonia | Opstina Bogomila | Opstina Bogovinje |
| Opstina Bogovinje, Republic of Macedonia | Opstina Bosilovo | Opstina Bosilovo, Republic of Macedonia |
| Opstina Brvenica | Opstina Brvenica, Republic of Macedonia | Opstina Capari |
| Opstina Capari, Republic of Macedonia | Opstina Caska | Opstina Caska, Republic of Macedonia |
| Opstina Cegrane | Opstina Cesinovo | Opstina Coka |
| Opstina Cucer-Sandevo | Opstina Cucer-Sandevo, Republic of Macedonia | Opstina Delcevo |
| Opstina Delcevo, Republic of Macedonia | Opstina Demir Hisar | Opstina Demir Hisar, Republic of Macedonia |
| Opstina Demir Kapija | Opstina Demir Kapija, Republic of Macedonia | Opstina Dobrusevo |
| Opstina Dolna Banjica | Opstina Dolneni | Opstina Dolneni, Republic of Macedonia |
| Opstina Drugovo | Opstina Drugovo, Republic of Macedonia | Opstina Dzepciste |
| Opstina Gradsko | Opstina Gradsko, Republic of Macedonia | Opstina Grocka |
| Opstina Ilinden | Opstina Ilinden, Republic of Macedonia | Opstina Izvor |
| Opstina Jegunovce | Opstina Jegunovce, Republic of Macedonia | Opstina Kamenjane |
| Opstina Kamenjane, Republic of Macedonia | Opstina Kanjiza | Opstina Karbinci |
| Opstina Karbinci, Republic of Macedonia | Opstina Karpos | Opstina Karpos, Republic of Macedonia |
| Opstina Kikinda | Opstina Kisela Voda | Opstina Kisela Voda, Republic of Macedonia |
