n. pl. plan·e·tar·i·ums or plan·e·tar·i·a (-ē-ə)
1. An apparatus or model representing the solar system.
a. An optical device for projecting images of celestial bodies and other astronomical phenomena onto the inner surface of a hemispherical dome.
b. A building or room containing a planetarium, with seats for an audience.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
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