roofstone

名词 n.
英 /ˈɹuːfˌstəʊ̯n/|/ˈɹʊf-/    美 /ˈɹufˌstoʊ̯n/|/ˈɹʊf-/|/ˈɹʉːfˌstəʉ̯n/|/ˈɹʊf-/

英文释义

名词 n.
  1. The stone or rock layer immediately above a coal seam.
    — The intention of the props is for the security of the workmen to keep up the roofstone; they have no effect in resisting the crush of the super-incumbent strata.
  2. A large, usually flat stone slab placed atop the side-stones (orthostats) of a megalithic burial chamber—such as in portal tombs, wedge tombs, or gallery graves—to form a roof covering the interior space.

词形变化

roofstones plural

词源

From roof + stone.
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