Oceanic eels [UK and USA], Familia – synonym of Derichthyidae, Familia
Odontostomops Fowler, 1934 – synonym of Odontostomops, Genus
Order Acipenseriformes, Ordo – synonym of Acipenseriformes, Ordo
Order Anguilliformes, Ordo – synonym of Anguilliformes, Ordo
Order Antheriniformes, Ordo – synonym of Antheriniformes, Ordo
Order Batrachoidiformes, Ordo – synonym of Batrachoidiformes, Ordo
Order Beloniformes, Ordo – synonym of Beloniformes, Ordo
Order Beryciformes, Ordo – synonym of Beryciformes, Ordo
Order Cetomimiformes, Ordo – synonym of Cetomomoformes, Ordo
Order Chimaerea, Ordo – synonym of Chimaerea, Ordo
Order Clupeiformes, Ordo – synonym of Clupeiformes, Ordo
Order Cyprinodontiformes, Ordo – synonym of Cyprinodontiformes, Ordo
Order Echeneiformes, Ordo – synonym of Echeneiformes, Ordo
Order Gadiformes, Ordo – synonym of Gadiformes, Ordo
Order Gasterosteiformes, Ordo – synonym of Gasterosteiformes, Ordo
Order Gobiesociformes, Ordo – synonym of Gobiesociformes, Ordo
Order Halosauriformes, Ordo – synonym of Halosauriformes, Ordo
Order Lampridiformes, Ordo – synonym of Lampridiformes, Ordo
Order Lophiiformes, Ordo – synonym of Lophiiformes, Ordo
Order Myxiniformes, Ordo – synonym of Myxiniformes, Ordo
Order Notacanthiformes, Ordo – synonym of Notacanthiformes, Ordo
Order Perciformes, Ordo – synonym of Perciformes, Ordo
Order Petromyzoniformes, Ordo – synonym of Petromyzoniformes, Ordo
Order Pleuronectiformes, Ordo – synonym of Pleuronectiformes, Ordo
Order Saccopharyngiformes, Ordo – synonym of Saccopharingiformes, Ordo
Order Scopeliformes, Ordo – synonym of Scopeliformes, Ordo
Order Scorpaeniformes, Ordo – synonym of Scorpaeniformes, Ordo
Order Syngnathiformes, Ordo – synonym of Syngnathiformes, Ordo
Order Tetraodontiformes, Ordo – synonym of Tetraodontiformes, Ordo
Order Zeiformes, Ordo – synonym of Zeiformes, Ordo
Oreos [UK and USA], Familia – synonym of Oreosomatidae, Familia
Orphies [France and Belgium], Familia – synonym of Belonidae, Familia
Orthotype: P. albipennis (Doderlein), by monotypy. – synonym of Photonectes, Genus
Other synonyms: Bertelsen, 1951: 57. – synonym of Himantolophus, Genus