- a drift, dug through ore, into which overlying material, especially from an upper layer of ore, is caved.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for sub-level
They knew the place as well as though the sub-level had been ablaze with light.
He left the cage at the sub-level just above the last level.
The men picked up the lad and bore him through the sub-level.
Come on up to the sub-level; we will begin our investigation there.
Whoever did the job, entered the skip shaft from sub-level seventeen.