dead-bolt

　ラスベガスで、ホームレスの男が、燃えているアパートから子供を救ったという記事からです。
Homeless man rescues children from burning apartment in Las Vegas, authorities say

A homeless man came to the rescue of two small children who were trapped inside a burning apartment in Las Vegas on Friday, authorities said.

Anival Angulo, 36, who is currently homeless, noticed smoke coming from an east Las Vegas apartment building and heard children crying as he was walking by the area just before noon on Friday. He jumped over a locked gate into the complex and saw smoke billowing through a barred security door of a smoldering apartment, according to a press release from Las Vegas Fire and Rescue.

Angulo saw a 3-year-old girl standing near the door inside the smoke-filled apartment, but the door was dead-bolt locked and she couldn't get out. So Angulo pulled on the steel bars of the door, bending it upward, causing the dead-bolt lock to unlatch. The door opened and the little girl ran to him, wrapping her arms around his waist, authorities said.

http://abcnews.go.com/US/homeless-man-rescues-children-burning-apartment-las-vegas/story?id=51530075

　取り上げる表現は"dead-bolt"です。そのまま直訳すると、「死んだねじ」となり、意味が通りません。『ジーニアス英和辞典』第４版（大修館）で調べてみると、「安全錠（ドアに埋め込み、ねじも外からは見えなくした協力錠）」とありました。これはアメリカ英語の表現であり、イギリス英語だと"mortise lock"や"dead lock"と表現されます。"dead"には「完全な、確実な」などの意味もあるため、「完全にねじで施錠する」というニュアンスで覚えられるかと思います。LDOCEでは、"a strong lock often used on doors"と定義されています。(Akim)