impenetrable /im-penˈi-trə-bl/

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

impenetrabilˈity noun

• the other side
• the other side of the coin
• the other woman
• the other world
• theotokoi
• theotokos
• the ould sod
• theow
• theows
• the Oxford group
• the Paris Commune
• the party's over
• the Peninsula
• the penny drops
• the period
• the permissive society
• the piece
• the pill
• the pips
• the pits
• the plot thickens
• the potato
• the pot calling the kettle black
• the powers that be
• the Preacher