| adit |
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noun
- A horizontal or nearly horizontal passage from the surface into a mine as contrasted to a shaft which is a vertical entry passage. An adit may be used for ventilation, haulage, drainage, or other purposes.
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| air shaft |
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noun
- a vertical (or near vertical) shaft that supplies ventilation to a tunnel or other underground facility
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| airway |
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noun (pluralairways)
-
(anatomy) The trachea.
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| anthracite |
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noun
- A form of carbon; the hardest and cleanest-burning of all the coals.
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