optic canal - ovaritis
- orrhorrhea
- orrhotherapy
- orris
- orthergasia
- orthesis
- orthetic
- orthetics
- orthetist
- ortho
- orthoamblyophore
- orthoamitosis
- orthoarteriotony
- orthobiosis
- orthocephalic
- orthocephalous
- orthocheilia
- orthochorea
- orthochromasia
- orthochromatic
- orthochromia
- orthochromophil
- orthocresol
- orthocytosis
- orthodactylous
- orthodentin
- orthodeoxia
- orthodiagram
- orthodiagraph
- orthodiagraphy
- orthodiascope
- orthodiascopy
- orthodichlorobenzene
- orthodigita
- orthodontal care
- orthodontia
- orthodontic
- orthodontic apparatus
- orthodontic appliance
- orthodontic appliances
- orthodontic arch