1. (physics) having dimension zero; expressable as a pure number not needing any units
   "any ratio of masses is dimensionless"

Encyclopedia: Dimensionless

• 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
• Oryzopsis miliacea
• orzo
• os
• os breve