wayboard (plural wayboards)
- (geology, mining) A thin layer or band of rock that separates or defines the boundaries of thicker strata.
1905, Institution of Mining and Metallurgy (Great Britain), Transactions of the Institution of Mining & Metallurgy, volume 15, page 176:
- In the Mill Close Mine, a very rich and extensive flat occurred under a way-board which was topped with a tiny coal seam 1 in. thick or so, the way-board itself being from 1 to 3 ft. thick, and looking very much like an […]