Sleeping Rent
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
In English law
An expression frequently used in coal-mine leases and agreements for the same. It signifies a fixed or dead, i. e., certain, rent, as distinguished from a rent or royalty varying with the amount of coals gotten, and is payable although the mine should not be worked at all, bnt should be sleeping or dead, whence the name.
Brown.