Entry 1 sense Webster, 1913 Cygnus /(s?g"n?s)/ · Cyg·nus · IPA /ˈsɪɡnəs/ 01 n. A constellation of the northern hemisphere east of, or following, Lyra; the Swan. 1. A constellation of the northern hemisphere east of, or following, Lyra; the Swan.(Astron.)