Main Entry: ar·mil·la·ry sphere

Pronunciation: \ˈär-mə-ˌler-ē-, är-ˈmi-lə-rē-\

Function: noun

Etymology: French sphère armillaire, from Medieval Latin armilla, from Latin, bracelet, iron ring, from armus shoulder — more at arm

Date: 1664

: an old astronomical instrument composed of rings showing the positions of important circles of the celestial sphere