impenetrable /im-penˈi-trə-bl/

1. Incapable of being penetrated
2. Impervious
3. Inscrutable
4. Occupying space exclusively (physics)

• clary
• clash
• clashed
• clasher
• clashers
• clashes
• clashing
• clashings
• clash-ma-clavers
• clasp
• clasped
• clasper
• claspers
• clasping
• claspings
• clasp knife
• clasp knives
• clasps
• class
• class.
• classable
• class action
• class actions
• class-book
• class-books