When people say there’s been an “𝑥 fold increase in such and such.” They mean such and such is 𝑥 times as big.
If you get something that actually folds like a sheet of paper, the amount of layers doubles each time. One fold = twice as many layers. Two folds = four times as many layers…
It’s not “two fold,” it’s “twofold”. And by extension, “threefold.” The “fold” here is not an independent word with its own meaning.
Yeah, 'number’fold words in modern English are actually linguistic hold overs from before ‘fold’ was a verb that meant to bend something along a crease.
https://www.etymonline.com/word/twofold
In a whole bunch of proto-English languages, fold or feald or fald or falt were all multiplicative suffixes (basically) attached to a number, which made a new word meaning to multiply by the number.
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I’d be willing to bet this is also why the phrase ‘doubled over’ literally means that a person is bent, or folded at their abdomen.
You take the new meaning of fold (to bend along a crease) but replace it with the word that twofold literally means (doubled).
If you interpreted ‘doubled over’ as literally as OP is taking twofold, then the phrase should mean that a person was above something and then spontaneously grew a clone of themselves, or became twice as heavy or tall or something.
This is actually pretty interesting. I wish I could pin someone else’s comment. Thanks.
NP! =D
It took me way too long to realise you weren’t asserting an unorthodox answer to the nondeterministic polynomial time problem.