Secure Lock That Is Harder to Open Without a Key

This page is the CodyCross answer for the clue below from Night Life, Group 1754, Puzzle 5 (Do Not Disturb).

Question is: Secure Lock That Is Harder to Open Without a Key

and the answer is: DEADBOLT

Word Meaning:

DEAD BOLT — Alternative form of deadbolt.

Definitions from Wiktionary.