n.
Pronunciation: ˌ pla-n ə - ' ter- ē - ə m
Function: noun
Inflected Form: plural -i · ums or -ia \ - ē - ə \
Date: 1734
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