Dead Hung

Slang term typically meaning a batten which is permanently fixed in one location and can't be raised and lowered. Typically this batten will be chained directly to structural I-beams that run above the stage.
Dead Hung can also refer to lighting instruments placed on a batten and raised out of the way for storage.

Also refers to set pieces that are chained or in some other way affixed to the structural I-beams that run above the stage.