/ Dictionary / Index S sonic depth finder: Meaning and Definition of Find definitions for: son'ic depth' find"er Pronunciation: [key] a sonar instrument that uses echolocation to measure depths under water. Cf. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. sonic boom sonic mine Related Content Daily Word Quiz: paradox Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language