1. (v. t.) To enter into; to make way into the interior of; as, light penetrates darkness.

2. (v. t.) To affect profoundly through the senses or feelings; to touch with feeling; to make sensible; to move deeply; as, to penetrate one's heart with pity.

3. (v. t.) To pierce into by the mind; to arrive at the inner contents or meaning of, as of a mysterious or difficult subject; to comprehend; to understand.

4. (v. i.) To pass; to make way; to pierce. Also used figuratively.