Unpenetrable
Pronunciation : Un*pen"e*tra*ble
Part of Speech : a.
Definition : Defn: Impenetrable.
Source : Webster's Unabridged Dictionary, 1913
Merriam-Webster's Everyday Language Reference Set: Includes: The Merriam-Webster Dictionary, The Merriam-Webster Thesaurus, and The Merriam-Webster Vocabulary Builder