Refers to a less-traveled path or a shortcut, often implying a quicker or alternative route. Can be used literally or figuratively.
彼は間道を使って時間を節約した。
He saved time by taking a shortcut.
Only locals know this side road.
Compound of 間 (kan, 'interval, between') and 道 (dō, 'road, path'), literally meaning 'between road' or 'side road'. The exact historical derivation is uncertain, but the meaning is transparent from its components.