impenetrable /im-penˈi-trə-bl/

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

• oughtnesses
• oughts
• ouglie
• ouguiya
• Ouija
• Ouijas
• ouistiti
• ouk
• ouks
• oulachon
• oulakan
• ould
• oulk
• oulks
• oulong
• oulongs
• ouma
• oumas
• ounce
• ounces
• oundy
• oup
• OUP
• oupa
• oupas