/ Dictionary / Index A agonic line: Meaning and Definition of Find definitions for: agon'ic line' Pronunciation: [key] an imaginary line on the surface of the earth connecting all points at which the declination of the magnetic field of the earth is zero. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. agonic agonist Related Content Daily Word Quiz: perspicacious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language