Breadcrumb Home > Dictionary > Index I instantaneous sound pressure: Meaning and Definition of Find definitions for: in'stanta'neous sound' pres"sure Pronunciation: [key] — Physics. Physics. See(def. 1). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. instantaneous instant camera ✖ Related Content Daily Word Quiz: donnybrook Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language