Astronomical image processing software. The meaning of ASTRONOMICAL is of or relating to astronomy. How to use astronomical in a sentence. Of enormous magnitude; immense: an astronomical increase in the deficit. connected with…. ASTRONOMICAL definition: of, relating to, or connected with astronomy. Feb 21, 2026 · Adjective astronomical (comparative more astronomical, superlative most astronomical) (not comparable, astronomy) Of or relating to astronomy. Definition of astronomical adjective in Oxford Advanced Learner's Dictionary. Of or relating to astronomy. Feb 23, 2026 · Discover the best astronomical events of 2026, including solar and lunar eclipses, meteor showers, planetary oppositions, and rare skywatching highlights. An astronomical amount is extremely large: 3.