I have been long fascinated by word phrases that we use in our everyday conversation, that, when taken literally, make no sense. Why did someone call an exam a "turkey shoot?" Or why am I "barking up the wrong tree" when I am looking for my skinflint aunt to send me money on my birthday? Why am I looking for a "square meal?" Won't a round one do? I love these things!
One such phrase that has puzzled me for a long time is "dead as a doornail." A doornail was never alive, so can it be dead? And why a door nail? Is this a good thing? hmmmm
Well I found a site that has some of the answers to the origin of phrases and here is what "dead as a doornail" implies:
"Meaning: To be dead, with no chance for recovery.
Example: You might as well junk that car, the engine is dead as a door nail.
Origin: Nails were once hand tooled and costly. When an aging cabin or barn was torn down the valuable nails would be salvaged so he could reuse them in later construction.
When building a door however, carpenters often drove the nail through then bent it over the other end so it couldn't work its way out during the repeated opening and closing of the door. When it came time to salvage the building, these door nails were considered useless, or "dead" because of the bend."
I found this information at Origins of Phrases.
