1. Living or active in the absence of free oxygen
   - anaerobic

See also: anaerobe

• Okapia
• Okapia johnstoni
• okay
• Okeechobee
• Okeechobee Waterway
• Okefenokee Swamp
• okeh
• Oken
• Okenfuss
• okey
• okey-doke
• okey-dokey
• Okinawa
• Okinawa campaign
• Oklahoma
• Oklahoma City
• Oklahoman
• okra
• okra plant
• okta
• Oktoberfest
• ola
• Olaf II
• Olav II
• old