/ Dictionary / Index I infrasonic: Meaning and Definition of Find definitions for: in•fra•son•ic Pronunciation: (in"fru-son'ik), [key] — adj. noting or pertaining to a sound wave with a frequency below the audio-frequency range. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: infrasonic (Thesaurus) infrared star infrasonics 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