plan·e·tar·i·um 
(plăn′ĭ-târē-əm)
(plăn′ĭ-târē-əm)n. pl. plan·e·tar·i·ums or plan·e·tar·i·a (-ē-ə)
1. An apparatus or model representing the solar system.
2.
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.
- Indo-European root: pā-
- Indo-European root: pāl-
- Indo-European root: pē(i)-
- Indo-European root: pō(i)-
- Indo-European root: pū̆-
- Indo-European root: pəter-
- Indo-European root: re-
- Indo-European root: reg-
- Indo-European root: rei-
- Indo-European root: reidh-
- Indo-European root: reig-
- Indo-European root: rep-
- Indo-European root: ret-
- Indo-European root: reudh-
- Indo-European root: reug-
- Indo-European root: reup-
- Indo-European root: reuə-
- Indo-European root: rē-
- Indo-European root: rēd-
- Indo-European root: r̥tko-
- Indo-European root: sak-
- Indo-European root: sal-
- Indo-European root: sed-
- Indo-European root: segh-
- Indo-European root: sek-