drop bolt

noun — 2 senses

drop bolt

noun

1

A bolt that holds a trapdoor shut.

Speaking now as a condemned criminal might speak ere the drop-bolts are drawn, my story, wild and hideously improbable as it may appear, demands at least attention.1888, Rudyard Kipling, “The Phantom Rickshaw”, in The Phantom 'Rickshaw and Other Tales, Allahabad: A.H. Wheeler and Co., page 9:

2

A bolt that drops into place when let go.

Entry derived from the Wiktionary, under licence CC BY-SA 4.0 — list of authors.