/ Dictionary / Index E extremely low frequency: Meaning and Definition of Find definitions for: extreme'ly low' fre'quency Pronunciation: [key] — Radio. Radio. any frequency between 30 and 300 hertz. Abbr.: ELF, elf Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. extremely high frequency extreme unction Related Content Daily Word Quiz: sinister Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language