astronomical

adjective

as·​tro·​nom·​i·​cal ˌa-strə-ˈnä-mi-kəl 

variants or less commonly astronomic

ˌa-strə-ˈnä-mik 

1

: of or relating to astronomy

astronomical observations

2

: enormously or inconceivably large or great

astronomical numbers

an astronomical price

astronomically

ˌa-strə-ˈnä-mi-k(ə-)lē 

adverb

Synonyms

• Brobdingnagian
• bumper
• colossal
• cosmic
• cosmical
• cyclopean
• elephantine
• enormous
• galactic
• gargantuan
• giant
• gigantesque
• gigantic
• grand
• herculean
• heroic
• heroical
• Himalayan
• huge
• humongous
• humungous
• immense
• jumbo
• king-size
• king-sized
• leviathan
• mammoth
• massive
• mega
• mighty
• monster
• monstrous
• monumental
• mountainous
• oceanic
• pharaonic
• planetary
• prodigious
• super
• super-duper
• supersize
• supersized
• titanic
• tremendous
• vast
• vasty
• walloping
• whacking
• whopping

Examples of astronomical in a Sentence

The cost of the office building was astronomical.

We got an astronomical telephone bill this month.

Recent Examples on the Web

Although parts of California have already experienced triple-digit temperatures, the new season doesn’t officially arrive until the summer solstice — an astronomical event that marks the longest day of the year. —Hannah Poukish, Sacbee.com, 8 June 2025

The summer solstice is an astronomical event marking the official start of summer in the Northern Hemisphere. —Emese MacZko, Forbes.com, 6 June 2025

Cheng and his colleagues made the discovery by searching through astronomical images from the Victor M. Blanco Telescope and the Canada France Hawaii Telescope for bright spots that might represent a TNO. —Margherita Bassi, Smithsonian Magazine, 29 May 2025

Negotiating strategy Trump’s approach to negotiations has involved threats of astronomical tariffs — up to 145% in the case of China — before striking a deal for far lower levels. —David McHugh, Los Angeles Times, 28 May 2025

Word History

Etymology

Late Latin astronomicus "of or relating to astronomy" (borrowed from Greek astronomikós "of astronomy, skilled in astronomy," from astronomía astronomy + -ikos -ic entry 1) + -al entry 1

First Known Use

1551, in the meaning defined at sense 1

Phrases Containing astronomical

• astronomical unit

Rhymes for astronomical

• anatomical
• economical
• comical
• neuroanatomical
• uneconomical

Kids Definition

astronomical

adjective

as·​tro·​nom·​i·​cal ˌas-trə-ˈnäm-i-kəl 

variants also astronomic

-ˈnäm-ik 

1

: of or relating to astronomy

2

: extremely or unbelievably large

the cost was astronomical

astronomically

-ˈnäm-i-k(ə-)lē 

adverb