- Octodenary Adj Noun
- Octofluorocyclobutane Noun
- Octofoil Noun
- Octogenarian Adj Noun
- Octonary Adj Noun
- Octophobia Noun
- Octoploid Adj Noun
- Octopod Noun
- Octopole Noun
- Octopus Noun
- Octoroon Noun
- Octosyllable Noun
- Octree Noun
- Octroi Noun
- Octroy Noun Verb
- Octuple Adj Noun Verb
- Octuplets Noun
- Octuplicate Adj Noun Verb
- Octupling Noun
- Octyl Adj Noun
- Octyne Noun
- Ocularist Noun
- Oculist Noun
- Oculistics Noun
- Oculography Noun
- Oculometry Noun
- Oculomotor Noun Adj
- Oculomycosis Noun
- Oculomyodynamometry Noun
- Oculopathy Noun
- Oculoplastics Noun
- Oculoplethysmography Noun
- Oculopneumoplethysmography Noun
- Oculopressor Noun
- Oculus Noun
- Odalisque Noun
- Odd Adj Noun
- Oddball Noun Adj
- Oddfellow Noun
- Oddity Noun
- Oddment Noun
- Oddness Noun
- Ode Noun
- Odeon Noun
- Odessa Noun
- Odeum Noun
- Odin Noun
- Odiousness Noun
- Odium Noun
- Odograph Noun
- Odometer Noun
- Odontalgia Noun
- Odontitis Noun
- Odontoblast Noun
- Odontoclast Noun
- Odontodynia Noun
- Odontogenesis Noun
- Odontogeny Noun
- Odontogram Noun
- Odontograph Noun