1. Not penetrable by light
   - lightproof

See also: opaque

• Harold Urey
• Harold W. Kroto
• Harold Wilson
• harp
• harp seal
• harp-shaped
• harper
• Harper's Ferry
• Harpia
• Harpia harpyja
• harpist
• Harpo
• harpoon
• harpoon gun
• harpoon line
• harpoon log
• harpooneer
• harpooner
• harpsichord
• harpsichordist
• harpulla
• harpullia
• Harpullia cupanioides
• Harpullia pendula
• harpy