/ Dictionary / Index P plunge basin: Meaning and Definition of Find definitions for: plunge' ba"sin Pronunciation: [key] a cavity at the base of a falls or cataract, formed by the action of the falling water. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. plunge plunge pool Related Content Daily Word Quiz: simian Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language