/ Dictionary / Index I infrasound: Meaning and Definition of Find definitions for: in•fra•sound Pronunciation: (in'fru-sound"), [key] — n. sound with frequencies below the audible range. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. infrasonics infraspecific Related Content Daily Word Quiz: fabricate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language