waterproof(noun, adjective, verb) adjective1. not permitting the passage of waterSimilar word(s): tight, rainproof, waterproofed noun1. any fabric impervious to waterDefinition categories: man–made, cloth, fabric, material, textile2. a water-resistant coatSimilar word(s): raincoatDefinition categories: man–made, coat verb1. make watertight- Waterproof the coatDefinition categories: contact, seal