planetarium

noun

plan·​e·​tar·​i·​um ˌpla-nə-ˈter-ē-əm 

plural planetariums or planetaria ˌpla-nə-ˈter-ē-ə 

1

: a model or representation of the solar system

2

a

: an optical device for projecting various celestial images and effects

b

: a building or room housing such a projector

Examples of planetarium in a Sentence

Recent Examples on the Web

The telescopes are weather-permitting, but either way, indoor activities including a planetarium show are also scheduled. —Jared Kaufman, Twin Cities, 23 Apr. 2026

For a dose of culture, head to the Newark Museum of Art, which boasts a planetarium and a garden along with its art collection. —Lauren Dana Ellman, Travel + Leisure, 21 Apr. 2026

Then take a break for a laser or planetarium show in the Digital Dome. —Nicole Letts, Southern Living, 14 Apr. 2026

Venus and Jupiter should also be visible, said Scott Kardel, associate professor of astronomy and the assistant planetarium director at Palomar College. —Maura Fox, San Diego Union-Tribune, 13 Apr. 2026

Word History

First Known Use

1860, in the meaning defined at sense 1

Rhymes for planetarium

• aquarium
• herbarium
• ovarium
• puparium
• samarium
• zoarium
• armamentarium
• cerium
• honorarium
• sanitarium

Kids Definition

planetarium

noun

plan·​e·​tar·​i·​um ˌplan-ə-ˈter-ē-əm 

plural planetariums or planetaria -ē-ə 

1

: a device that projects images of heavenly bodies on a ceiling shaped like a dome

2

: a building or room housing a planetarium