The term 'ENTRANCE INTO A MINE' can be summarized as an ADIT, which is a four-letter word. An ADIT is an entrance or access point to a mine, typically a horizontal tunnel that is dug into the side of a mountain or hill. It is used to provide ventilation and access for miners to reach the ore deposits inside the mine. Adits are also used to drain water from the mine and to transport ore out of the mine.