planetarium
/ˌplænəˈterijəm/
noun
plural
planetariums
or
planetaria
/-ijə/
/ˌplænəˈterijə/
plural
planetariums
or
planetaria
/-ijə/
/ˌplænəˈterijə/
Learner's definition of PLANETARIUM
[count]
:
a building or room in which images of stars, planets, etc., are shown on a high, curved ceiling