/ Dictionary / Index N natural logarithm: Meaning and Definition of Find definitions for: nat'ural log'arithm Pronunciation: [key] — Math. Math. a logarithm having e as a base. Symbol: ln Also calledCf. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. natural levee naturally Related Content Daily Word Quiz: frugal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language