adit(redirected from adits)
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adit(ăd`ĭt), in mining, underground passage excavated nearly horizontally, with one end open to the earth's surface, usually used to service a mine. The adit end is the furthermost end from the surface, i.e., the location where miners work. The adit collar is the area where an adit opens to the surface and must be reinforced against any surface weakness.
a horizontal or inclined excavation that has an outlet to the surface and is designed to facilitate mining operations. Adits can be exploratory or used for working deposits. Transport, ventilation, and water-removal adits are distinguished, depending on their purpose.