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astronomy

n.
US //əˈstɹɑnəmi// UK //ɐstɹˈɒnəmi// as·tron·o·my
  1. 1 scientific study of space (n.)
    B1 Intermediate Science

    the scientific study of the stars, planets, and other objects in the universe.

    the scientific study of celestial objects and phenomena, including the physics, chemistry, and evolution of the universe beyond Earth's atmosphere.

    Example

    He spent his childhood reading books about astronomy and looking at the moon through a telescope.

    Example

    Advances in radio astronomy have allowed researchers to observe distant galaxies that remain invisible to traditional optical telescopes.
    Pitfall
    She is interested in astrology and the stars in the galaxy.
    She is interested in astronomy and the stars in the galaxy.

    Astronomy is the science of space; astrology is the belief that stars influence human lives.

  2. 2 astrology (n.)
    C2 Proficiency Archaic

    an old word for astrology, which is the belief that stars affect people's lives.

    a historical synonym for astrology, referring to the divination of supposed influences of the stars and planets on human affairs.

    Example

    In very old books, the word astronomy sometimes meant predicting the future by the stars.

    Example

    In certain Renaissance texts, the distinction between astronomy and astrology was blurred, with the former often encompassing the practice of casting horoscopes.

    Teacher's tip

    This sense is archaic; modern speakers strictly distinguish between the science of astronomy and the pseudoscience of astrology.
Origin

From Middle English astronomie, astronemy, from Old French astronomie, equivalent to astro- + -nomy. Displaced native Old English tungolcræft.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

Word family

Last updated June 20, 2026