天てん険けん

noun

natural defenses; steep place

Refers to a naturally fortified location, such as a steep mountain or cliff, that provides defensive advantage. Often used in historical or geographical contexts.

• その城しろは天てん険けんを利り用ようして建たてられた。

  The castle was built taking advantage of the natural defenses.

• この山やま道みちは天てん険けんの地ちとして知しられている。

  This mountain path is known as a place of natural fortification.