1. Wild sheep of mountainous regions of western North America having massive curled horns
   - bighorn, bighorn sheep, cimarron, Rocky Mountain sheep, Ovis canadensis

Type of: mountain sheep

Part of: genus Ovis, Ovis

• orthotropous ovule
• Ortilis vetula macalli
• ortolan
• ortolan bunting
• ortygan
• Orudis
• Orudis KT
• Orumiyeh
• Oruvail
• Orville Wright
• Orwell
• Orwellian
• Orycteropodidae
• Orycteropus
• Orycteropus afer
• Oryctolagus
• Oryctolagus cuniculus
• oryx
• Oryx gazella
• Oryza
• Oryza sativa
• Oryzomys
• Oryzomys palustris
• Oryzopsis
• Oryzopsis hymenoides