spring gun

plural spring guns

1. A gun rigged to fire when a tripwire is crossed.

   1 more example

   A prevalent custom is the "pomali," exactly equivalent to the "taboo" of the Pacific islanders, and equally respected. It is used on the commonest occasions, and a few palm leaves stuck outside a garden as a sign of the "pomali" will preserve its produce from thieves as effectually as the threatening notice of man-traps, spring guns, or a savage dog would do with us.

   1869, Alfred Russel Wallace, The Malay Archipelago, volume I, London: Macmillan and Co., page 306