Doornail

Part of speech: noun

Definitions

1. A stout nail with a broad, rounded head, once hammered through old wooden doors for strength and decoration ; an idiom meaning utterly lifeless, used with the word dead
2. A heavy nail with a large domed head traditionally driven into timber doors ; a set phrase describing something or someone completely and unmistakably dead
3. An iron nail with a big ornamental head used to fix planks on a door ; a colloquial expression in the phrase dead as this nail, meaning totally lifeless

Etymology: The phrase "dead as a doornail" is older than the word alone suggests. "Doornail" itself is a compound of "door" and "nail," and it originally named the large, flat-headed nail driven through a door's planks. Such nails were struck hard and clinched on the far side, so they were thought of as firmly fixed and, by extension, lifeless and immovable. The image of the doornail as something utterly inert is what gave the phrase its force. Once a thing had no more motion or life in it than a driven nail, it was simply dead. The sense of the word as a fixed, unmoving object carried over into the idiom, and the word is now almost never used outside that expression.