/ Dictionary / Index S scanning line: Meaning and Definition of Find definitions for: scan'ning line" Pronunciation: [key] (in a cathode-ray or television tube) a single horizontal trace made by the electron beam in one traversal of the fluorescent screen. Cf.(def. 9). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. scanning electron microscope scanning tunneling microscope Related Content Daily Word Quiz: pundit Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language