/ Dictionary / Index M mean line: Meaning and Definition of Find definitions for: mean' line" Pronunciation: [key] an imaginary x-high line. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. mean life meanly Related Content Daily Word Quiz: placid Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language