1. Lacking thorns
   - spineless

See also: unarmed

• optical
• optical aberration
• optical activity
• optical art
• optical bench
• optical character recognition
• optical condenser
• optical crown
• optical crown glass
• optical density
• optical device
• optical disc
• optical disk
• optical fiber
• optical fibre
• optical flint
• optical fusion
• optical glass
• optical illusion
• optical instrument
• optical lens
• optical maser
• optical opacity
• optical phenomenon
• optical prism