ADV. deep, deeply, far caves penetrating deep into the hills | fully, totally | hardly The sunlight hardly penetrated the inner room. | quickly | slowly The news slowly penetrated his consciousness. | easily, readily These so-called secret societies were easily penetrated by intelligence agents. | successfully
VERB + PENETRATE be able to, can/could | be difficult to | seem to The cold seemed to penetrate his bones. | fail to | allow sth to Cut two slashes on each side of the fish to allow heat to penetrate.
PREP. into It is not yet known how deeply the radiation has penetrated into the soil. | through The light could not penetrate through the thick curtains. | to The dust had penetrated to all corners of the room.