intentionally curved road section; defensive bend in a road
Refers to a deliberate curve or zigzag in a road, historically designed to slow attackers or impede visibility. Often used in descriptions of castle approaches or old town layouts.
In the castle town, intentionally curved road sections were built to prevent enemy intrusion.
This road bends sharply, so you can't see what's ahead.
Compound of 鍵 (かぎ, 'key') + の (possessive particle) + 手 (て, 'hand; shape'). The term likens the sharp, right-angled bend of a road to the shape of an old-fashioned key.