Define: Adit

Adit (noun):
1. A horizontal or nearly horizontal passage leading into a mine or underground excavation, typically used for access, drainage, or ventilation.
2. A tunnel or passage excavated into a hillside or mountain for various purposes, such as transportation, irrigation, or storage.
3. In geology, a horizontal or gently sloping entrance or opening into a cave or underground cavity.
4. In architecture, a small, narrow entrance or passage leading into a building or structure, often serving as a secondary or private access point.
5. In hydrology, a man-made tunnel or channel constructed to divert water from a river or stream for irrigation or other purposes.