astrophysics

1 of 2

noun

as·​tro·​phys·​ics ˌa-strə-ˈfi-ziks 

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 

adjective

astrophysically

ˌa-strə-ˈfi-zi-k(ə-)lē 

adverb

astrophysicist

ˌa-strə-ˈfi-zə-sist 

-ˈfiz-sist

noun

astrophysical

2 of 2

adjective

as·​tro·​phys·​i·​cal ¦a-strə-¦fi-zi-kəl 

: of or relating to astrophysics

astrophysically adverb

Astrophysically, the understanding of the nature and properties of the interstellar gas is of the first importance since it is out of this medium that new stars are formed.

—Malcolm Longair, The New Physics, 1989

Examples of astrophysics in a Sentence

Recent Examples on the Web

Noun

Did the instruction manual for assembly look like it could have been ripped out of an astrophysics textbook? — Kate McGregor, Architectural Digest, 23 Jan. 2026

The findings have implications for developing nuclear fusion technology and for astrophysics research. — Aman Tripathi, Interesting Engineering, 9 Aug. 2025

Word History

Etymology

Noun

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.")

Adjective

astr- + physical

First Known Use

Noun

1870, in the meaning defined above

Rhymes for astrophysics

• geophysics
• metaphysics
• physics
• tectonophysics

Kids Definition

astrophysics

noun

as·​tro·​phys·​ics ˌas-trə-ˈfiz-iks 

: a branch of astronomy dealing with the physical and chemical measurements of the heavenly bodies

astrophysical

-ˈfiz-i-kəl 

adjective

astrophysicist

-ˈfiz-ə-səst 

noun