/ Dictionary / Index C Cygnus X-1: Meaning and Definition of Find definitions for: Cygnus X-1 Pronunciation: (eks'wun'), [key] — Astron. Astron. a strong x-ray source in the constellation Cygnus, consisting of a binary system of which one component may be a black hole. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Cygnus A cyke Related Content Daily Word Quiz: careening Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language