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Note: Tracking the origins of phrases is impossible most of the time! Mostly, what you'll find are the popular theories as to how an idiom originated, but it may or may not be necessarily so. 

In addition, quotes containing a particular phrase are usually taken from old newspapers, poems, or books that were written centuries ago, but this does not mean that the phrase originates from said newspapers, poems, or books. In all likelihood, if an expression is being used in a newspaper, it's probably already a well known saying and is thus from an older time. With that said, old quotes give some indication on how old a saying is.
Someone or something that looks to be defeated, or nearly so. A term used in boxing, refers to a downed boxer who tries to get back to his feet before the ref counts to ten.
It's believed that this phrase comes from boxing. Boxers throw out punches in an attempt to knock their opponent down or out. If a boxer does get knocked down from a punch, then the referee starts to slowly count to ten. During this time, the downed boxer has to stand back up on his feet in order for the fight to continue. However, if he fails to do so, then it is ruled that he's been knocked out and the fight ends. Thus, being "down for the count" refers to the time when a boxer is knocked down and the referee begins counting.

The earliest I could find this phrase is in the Newark Daily Advocate newspaper, 1900:

"Jack root, the undefeated middleweight of Chicago at Tattersall's obtained the decision over Dick O'Brien 
of Lewiston, Maine, at the end of six rounds, after one of the fiercest battles ever witnessed in this city. 
O'Brien was in poor condition or probably the result would have been different, as he had Root down for 
the count three times in the second round."
* The basketball team I was rooting for was down by 20 points in the 4th quarter, so I considered them to be down for the count. However, that was not the case because they came back and won the game during the last few minutes.

* The grass in my backyard is turning yellow because I haven't been watering it regularly. I think the grass may be down for the count, but I'll try watering it to see if that helps.
The meaning of the phrase Down for the Count!
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The letter D - Phrases starting with the letter D!
Phrases and Idioms
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