/ Dictionary / Index P penetration: Meaning and Definition of Find definitions for: pen•e•tra•tion Pronunciation: (pen"i-trā'shun), [key] — n. the act or power of penetrating. mental acuteness, discernment, or insight: a scholar of rare penetration. the obtaining of a share of a market for some commodity or service. the extension, usually peaceful, of the influence of one nation or culture into the affairs of another. a military attack that penetrates into enemy territory. the depth to which a projectile goes into the target. the measure of relative depth of field of a telescope or microscope, esp. a binocular microscope. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: penetration (Thesaurus) penetrating penetration aid Related Content Daily Word Quiz: spectral Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language