- a combining form with the meaning “pertaining to stars or celestial bodies, or to activities, as spaceflight, taking place outside the earth's atmosphere,” used in the formation of compound words: astronautics; astrophotography.
Origin of astro-
- indicating a heavenly body, star, or star-shaped structureastrology; astrocyte
- indicating outer spaceastronautics
Word Origin and History for astro-
element active in English word formation from mid-18c. and meaning "star or celestial body; outer space," from Greek astro-, stem and comb. form of astron "star," related to aster "star" (see star (n.)). In ancient Greek, aster typically was "a star" and astron mostly in plural, "the stars." In singular it mostly meant "Sirius" (the brightest star).
- A prefix that means star (as in astrophysics), celestial body (as in astronomy), or outer space (as in astronaut).