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

For the most accurate location-specific information, consult online planetariums like Stellarium. —Jamie Carter, Forbes.com, 31 May 2026

Inside, the museum boasts a planetarium, giant-screen theater, exhibition zones, and landscaped outdoor teaching plots organized around regional species and observable plant phenomena. —Bridget Borgobello may 30, New Atlas, 30 May 2026

Its arrival signals the return of the Loch Haven Park museum’s big-screen presentations plus planetarium shows and laser-light shows. —Dewayne Bevil, The Orlando Sentinel, 26 May 2026

With its curved ceiling, the 120-seat auditorium serves not just as a film and laser show venue but also as a planetarium. —Veronica Fernandez-Alvarado, Sacbee.com, 16 May 2026

Word History

First Known Use

1860, in the meaning defined at sense 1

Rhymes for planetarium

• aquarium
• herbarium
• ovarium
• puparium
• samarium
• solarium
• 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