v. pen·e·trat·ed, pen·e·trat·ing, pen·e·trates
1. To enter, pass into, or force a way into: The needle penetrated the skin. Light penetrated the forest canopy. The soldiers penetrated enemy territory.
a. To enter into and permeate: The sound of the piano penetrated each room of the house.
b. To affect deeply, as by being known or by arousing the emotions: "Literature should penetrate all the chambers of the human heart, even the dark ones" (Robert Cormier).
a. To insert the penis, a finger, or an object into the vagina or anus of (someone).
b. To insert something into (the vagina or anus).
4. To enter (an organization, for example), usually surreptitiously, so as to gain influence or information; infiltrate.
5. To enter and gain a share of (a market): penetrated the home-computer market with an affordable new model.
6. To grasp the significance of; understand: penetrate the workings of the immune system.
7. To see through: keen eyes that penetrate the darkness.
1. To enter or pass into something: The drill penetrated into the wood.
2. To have an effect or influence, especially on the mind or emotions: The culture of celebrity has penetrated into everyone's awareness.
3. To gain insight: tried to penetrate into the nature of the mind.
[Latin penetrāre, penetrāt-, from penitus, deeply.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.