忍しのび返がえし

noun

wall-top spikes; anti-intruder spikes

Refers to sharp spikes (often bamboo, wood, or iron) placed along the top of walls or fences to prevent thieves or intruders from climbing over. A traditional security feature.

• 古ふるい武ぶ家け屋や敷しきの塀へいには忍しのび返がえしが付ついている。

  The walls of the old samurai residence have anti-intruder spikes on top.

• 忍しのび返がえし