- Oceanaut Noun
- Oceaneering Noun
- Oceanfront Adj Noun
- Oceania Noun
- Oceanian Adj Noun
- Oceanicity Noun
- Oceanides Noun
- Oceanographer Noun
- Oceanography Noun
- Oceanologist Noun
- Oceanology Noun
- Oceanside Adj Noun
- Ocellus Noun
- Ocelot Noun
- Ocher Noun Adj
- Ochlocracy Noun
- Ochlophobia Noun
- Ochre Adj Noun
- Ochrometer Noun
- Ochronosis Noun
- Ocimene Noun
- Ocker Noun Adj
- Ockham Noun
- Ocotillo Noun
- OCR Noun
- Ocrea Noun
- Octachord Noun
- Octacylinder Noun
- Octad Noun
- Octadecyl Adj Noun
- Octafluorostyrene Noun
- Octagon Noun
- Octagram Noun
- Octahedrite Noun
- Octahedron Noun
- Octahemioctahedron Noun
- Octal Adj Noun
- Octamer Noun
- Octameter Noun
- Octanal Noun
- Octane Noun
- Octanol Noun
- Octanoyl Noun
- Octant Noun
- Octarchy Noun
- Octastich Noun
- Octastyle Adj Noun
- Octateuch Noun
- Octave Noun
- Octavia Noun
- Octavo Noun
- Octene Noun
- Octennial Adj Noun
- Octet Noun
- Octile Noun
- Octillion Noun
- October Noun
- Octobrist Noun
- Octocentenary Noun Adj
- Octodecimo Noun