Deadbolt (noun)

A type of lock that is typically used on a door and is engaged by turning a key or thumbturn, providing additional security against unauthorized entry.

Origin:

The term 'deadbolt' is derived from the old english words 'dead' and 'bolt', meaning a bolt that is not moved by the latch.

Examples:

1. The locksmith installed a new deadbolt on the front door to provide additional security.
2. The apartment door had a deadbolt, chain lock, and a peephole for added safety.
3. The deadbolt was stuck and wouldn't budge, even with the key in the lock.
4. The deadbolt was the only thing standing between the burglars and the valuable items inside the house.
5. The deadbolt on the door was so secure that even the fire department had trouble getting inside during the emergency.