/ Dictionary / Index Z zenith tube: Meaning and Definition of Find definitions for: ze'nith tube" Pronunciation: [key] — Astron. Astron. a telescope mounted to point only at the zenith, used at some observatories for measuring time by the stars. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. zenith distance Zeno Related Content Daily Word Quiz: ontiguous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language