astrophysics

noun

as·​tro·​phys·​ics ˌa-strə-ˈfi-ziks How to pronounce astrophysics (audio)
plural in form but singular or plural in construction
: a branch of astronomy dealing especially with the behavior, physical properties, and dynamic processes of celestial objects and phenomena
astrophysical
ˌa-strə-ˈfi-zi-kəl How to pronounce astrophysics (audio)
adjective
astrophysically
ˌa-strə-ˈfi-zi-k(ə-)lē How to pronounce astrophysics (audio)
adverb
astrophysicist
ˌa-strə-ˈfi-zə-sist How to pronounce astrophysics (audio)
-ˈfiz-sist
noun

Examples of astrophysics in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
The findings have implications for developing nuclear fusion technology and for astrophysics research. —Aman Tripathi, Interesting Engineering, 9 Aug. 2025 See All Example Sentences for astrophysics

Word History

Etymology

astro- + physics, probably after German Astrophysik

Note: The term Astrophysik was introduced by the German physicist Johann Karl Friedrich Zöllner (1834-82) in Photometrische Untersuchungen (Leipzig, 1865), pp. 315-16: "Sowohl die heutige Entwicklungsphase der Astronomie als auch das täglich sich steigernde Interesse für die Anwendung rein physikalischer Methode auf astronomische Objecte, scheinen anzudeuten, dass bereits gegenwärtig alle Elemente zur Bildung jenes neuen Theils der Astronomie vorhanden sind. Derselbe dürften vielleicht nicht unpassend mit dem Namen 'Astrophysik' belegt werden, zum Unterschiede von dem bisher in Deutschland allgemein als 'physische Astronomie' bezeichnete Theile.' ("Both the current phase of the development of astronomy and the interest, rising daily, in the applying purely the methods of physics to astronomical objects seem to indicate that all the elements for forming that new branch of astronomy are presently already at hand. This branch should perhaps not unsuitably be given the name 'astrophysics,' to distinguish it from the branches generally characterized up to now as 'physical astronomy' in Germany.")

First Known Use

1870, in the meaning defined above

Time Traveler
The first known use of astrophysics was in 1870

Rhymes for astrophysics

See All Rhymes for astrophysics

Browse Nearby Words

astrophyllite
astrophysics
Astrophyton
See all Nearby Words

Cite this Entry

“Astrophysics.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/astrophysics. Accessed 31 Oct. 2025.

Copy Citation

Share

Kids Definition

astrophysics

noun
as·​tro·​phys·​ics ˌas-trə-ˈfiz-iks How to pronounce astrophysics (audio)
: a branch of astronomy dealing with the physical and chemical measurements of the heavenly bodies
astrophysical
-ˈfiz-i-kəl How to pronounce astrophysics (audio)
adjective
astrophysicist
-ˈfiz-ə-səst How to pronounce astrophysics (audio)
noun
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Popular in Grammar & Usage

See More

'Affect' vs. 'Effect'

Using Bullet Points ( • )

'A' or 'an'? What about before 'h'? An Indefinite Article Guide

The Difference Between 'i.e.' and 'e.g.'

What’s the difference between ‘cemetery’ and ‘graveyard’?
See More

Popular in Wordplay

See More

Skibidi, Mog & More: Gen Alpha Slang

13 Wonderful Words That You're Not Using (Yet)

Ten More Words from Taylor Swift Songs

Why do we 'bury the lede?'

'Za' and 9 Other Words to Help You Win at SCRABBLE
See More

Popular

See More

'Affect' vs. 'Effect'

Skibidi, Mog & More: Gen Alpha Slang

13 Wonderful Words That You're Not Using (Yet)
See More

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
The Missing Letter A daily crossword with a twist
pastel colored puzzle piece speech bubbles with shadows
Quiz: Find the Missing Link Figure out the word that fits both halves of the ...
See All