- Orbit Terbuka
- Orbit Tertutup
- Orbit Tinggi Bumi
- Orbit; Edaran
- Orbital Antiikat
- Orbital Antiikat; Edar Antiikat
- Orbital Atom
- Orbital Degenerat
- Orbital Delta
- Orbital Ekapusat
- Orbital Hibrid
- Orbital Ikat
- Orbital Ikat Molekul
- Orbital Kosong
- Orbital Molekul
- Orbital Molekul (Pendekatan Lcao)
- Orbital Molekul Antiikat
- Orbital Molekul Berdaur
- Orbital Molekul Siklik
- Orbital Setengah-Terisi
- Orbital Sigma
- Orbital Slater
- Orbital Terlokalkan
- Orbitan Anti-Ikatan
- Orbitotomi
- Orbitotomi Lateral
- Orde Reaksi
- Orde Reaksi (Orde Proses)
- Order Multikutub
- Order Spin Pilin; Benahan Spin Pilin
- Ordinan Susu
- Ordinasi Euclides
- Ordo (Tanah)
- Ordo Kedua
- Ordo Tanah
- Ordovisium
- Orf
- Organ Afektor
- Organ Analog
- Organ Berbilik
- Organ Berlese
- Organ Bidder
- Organ Cahaya
- Organ Corti
- Organ Dwilobus
- Organ Eltringham
- Organ Endokrin
- Organ Gene
- Organ Golgi
- Organ Graber
- Organ Hemopoiesis
- Organ Hidrostatik; Keseimbangan
- Organ Jacobson
- Organ Johnston
- Organ Kadaver
- Organ Kepala
- Organ Kerik
- Organ Keseimbangan
- Organ Kopulasi
- Organ Kordotonal
- Organ Lekat
- Organ Liar
- Organ Limfoepitelium
- Organ Limfoid Periferi
- Organ Limfoid Primer
- Organ Limfoid Sekunder
- Organ Melira
- Organ Muller
- Organ Neurohema
- Organ Neurohemal
- Organ Palpus
- Organ Paraksial
- Organ Pembentuk Darah
- Organ Pendenyut
- Organ Perasa
- Organ Perifalus
- Organ Pseudostigma
- Organ Rasa Tarsus
- Organ Rembang
- Organ Reproduksi; Organ Perkembangbiakan