protective glass
transparent or translucent part of an open or closed luminaire designed to protect the electric light source(s) or other luminous element(s) from dust or dirt, or to prevent their contact with liquids, vapours or gases and to render them inaccessible
Note 1 to entry: This entry was numbered 845-10-39 in IEC 60050-845:1987.
Note 2 to entry: This entry was numbered 17-996 in CIE S 017:2011.