To succeed in forcing a way into or through a thing. The bullet was able to penetrate the thick armor of the vehicle.
To infiltrate or gain access to an organization, place, or system, especially when this is done surreptitiously or for a specific purpose. The spy managed to penetrate the enemy's headquarters without being detected.
To understand or grasp the true nature of something. It took him years to penetrate the complexities of quantum physics.
To affect or influence something deeply. Her words penetrated his heart, leaving a lasting impression.
To insert the penis into the body of a sexual partner during copulation. During intercourse, the man penetrated his partner carefully.