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 museum is also creating a Pixar Pass that will connect concepts from the exhibit to other parts of Frost, including the planetarium and aquarium. — Megan Fitzgerald, Miami Herald, 6 Oct. 2026

Bridgers capped off the unorthodox rollout by hosting worldwide release-week listening parties at planetariums. — Christine Werthman, Billboard, 5 Oct. 2026

Craft a miniature to add to Adam’s model town of Winter River, Connecticut, see ghosts at a science show, investigate sandworms on Titan, or visit Betelgeuse in the planetarium. — John Coffren, Baltimore Sun, 24 Sep. 2026

Her parents, who met at a planetarium, are in the crowd at Dye Creek. — Sean MacAday, Sacbee.com, 19 Sep. 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