A number of parts or facets; multiplied by such a number; relating to folding or to a folded object.
[Old English -fald, -feald, related to fold.]
This suffix forms adjectives and adverbs from the cardinal or counting numbers, so twofold, eightfold, hundredfold, thousandfold and many others. Related words are bifold, double or twofold; and manifold, many and various, or a thing with many different parts or forms (manyfold is a more recent equivalent with the sense of something increased many times).
The suffix also has the sense of folding: a gatefold is an oversized page in a book, folded inside but designed to be opened out to be looked at; in the US a billfold is a wallet designed to hold folded dollar bills. Other examples are linenfold, an ornamental motif resembling folded linen that is carved on panelling; and fanfold, continuous stationary folded concertina-fashion.
Blindfold does not belong here, as it is a modified form, on the model of words in -fold, of the Old English blindfeld, to cover the eyes or make blind; scaffold is another with a different origin—the unrelated Anglo-Norman French (e)schaffaut.