Pronunciation: /ɪmˈpɛnətrəbəl/
adjective not able to be penetrated or pierced; impossible to pass through or enter
A1 The castle had an impenetrable fortress wall.
A2 The encryption on the file was so impenetrable that no one could access it.
B1 The detective was faced with an impenetrable mystery that seemed unsolvable.
B2 The language barrier created an impenetrable wall between the two cultures.
C1 The scientist's research was so complex and impenetrable that only a few experts could understand it.
C2 The government's impenetrable security measures ensured the safety of classified information.
formal The fortress was surrounded by an impenetrable wall, making it nearly impossible to breach.
informal I tried to open the lock, but it seems impenetrable. I can't get it to budge.
slang The security on that website is so impenetrable, it's like Fort Knox!
figurative Her stoic demeanor made her seem impenetrable, but deep down she was very vulnerable.
impenetrated
impenetrables
more impenetrable
most impenetrable
impenetrates
will be impenetrable
has been impenetrable
is being impenetrable
impenetrable
impenetrable
to impenetrate
impenetrating
impenetrating