astro-

1. 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.

astro-

combining_form

1. indicating a heavenly body, star, or star-shaped structure

   astrology

   astrocyte

2. indicating outer space

   astronautics

astro–

1. A prefix that means “star” (as in astrophysics ), “celestial body” (as in astronomy ), or “outer space” (as in astronaut ).

Word History and Origins

Origin of astro-¹

< Greek, combining form of ástron a star, constellation, akin to astḗr star; aster, -aster ²

Word History and Origins

Origin of astro-¹

from Greek, from astron star

Example Sentences

A strange, antique, and classic grove,—nulli penetrabilis astro.

From Project Gutenberg

La Stampa "Un nuovo grande astro della litteratura inglese."

From Project Gutenberg

Salve, rayo perdido del astro deseado, que vienes a alegrar estos desiertos!

From Project Gutenberg

Al fin has brillado ante mis ojos, astro divino, manantial de luz, foco de la vida!

From Project Gutenberg

And I may say of him, as was said of a celebrated poet, Cui unquam poetarum magis proprium fuit subito astro incalescere?

From Project Gutenberg

Words That Use astro-

What does astro- mean?

Astro- is a combining form used like a prefix meaning “related to stars, celestial bodies, and outer space.” It is often used in scientific terms, especially in—you guessed it—astronomy.

Astro– is also sometimes used to refer to something that is star-shaped, as in an astrocyte, a type of star-shaped cell in the brain and spinal cord.

Astro- comes from the Greek ástron, meaning “star.” The Greek ástron is also related to such words as asteroid and even the star itself. The word astronomy comes from a Greek word that literally (and poetically) means “star-arranging.”

What are variants of astro-?

When combined with words or word elements that begin with a vowel, astro- becomes astr-.

Examples of astro-

You have likely heard of the word (and even dreamed of becoming an) astronaut.

As we know, astro- means “star.” How about -naut? It ultimately comes from the Greek naútēs, meaning “sailor.” Astronaut literally—and again, so poetically— translates to “star sailor.”

What are some other words that use the combining form astro-?

• astroarchaeology
• astroblastoma
• astrobleme
• astrobotany
• astrochemistry
• astrocompass
• astrocytoma
• astrodome
• astrodynamics
• astrology (via the equivalent form of astro- in Greek)
• astrogate
• astrogeology
• astroglia
• astrograph
• astrometry
• astrophysics

Learn about some other applications of astro- in our Vocab Builder article on Astroturf.

Similar to astro- are the combining forms cosmo- and cosm- (think cosmos). Learn more about these forms in our Words That Use cosmo- and Words That Use cosm- articles.

Break it down!

If navigating refers to moving ships in the water or planes in the sky, then what is astrogating?