the.com/deadbolt
The lock that doesn't trust the doorknob to do its one job.
means A locking bar that slides into the door frame with no spring action, so it can't be forced back by shoving or card-slipping like a regular latch.
from Straightforward compound of 'dead' + 'bolt' — 'dead' here meaning inert, fixed, without spring or mechanism of its own (as in 'dead weight'), and 'bolt' meaning the sliding metal bar itself, a sense going back to arrow-bolts and the bolts of old door and gate fastenings. Put together, the name just describes the thing: a bolt that stays put until a key or thumb-turn deliberately moves it, unlike a spring latch that gives under pressure.
- no spring
- moves only when you turn it, so prying can't shoot it back
- throw length
- at least one inch keeps it clear of the door frame gap
- grade rating
- ANSI Grade 1 survives ten strikes of 75 pounds force
- single vs double
- double-cylinder needs a key inside too, which can trap you in fires