|1.||indicating a heavenly body, star, or star-shaped structure: astrology; astrocyte|
|2.||indicating outer space: astronautics|
|[from Greek, from astron star]|
A prefix that means "star" (as in astrophysics), "celestial body" (as in astronomy), or "outer space" (as in astronaut).
American Society for Therapeutic Radiology and Oncology