Spill
Spill turns up in 2 fields: lighting, mining. Here is what it means to the people in each one.
Spill in lighting
Light that falls outside the area it is aimed at, onto walls, ceilings, audiences or neighbors.
Stray light around the edges of a beam, through gaps in shielding or off the back of a luminaire. On stage, spill lands on scenery or masking and is cut with shutters, barn doors or a top hat; on film sets it is controlled with flags; outdoors it becomes light trespass when it crosses a property line. Designers talk about spill when a beam or optic wastes light beyond its target.
"There's spill from the box boom hitting the proscenium, cut it with the top shutter before the run tonight."
Spill in mining
A heavy pole or lath driven horizontally into loose ground ahead of the main timbering.
In underground tunneling through soft or caving ground, miners drive these thick wooden or steel poles forward before excavating. The spills form a temporary roof or shield, protecting the crew while they muck out the loose material and install permanent sets. This technique is known as spiling or forepoling.
"Drive a few more spills over that next cap before we try to pull any more dirt out of the face."