Plural of fanfold; multiple sheets or examples of paper folded in the fan or accordion style, or as a verb, the action of folding something in this manner.
From fanfold (fan + fold) plus the plural -s, or from the verb form meaning to apply fanfold-style folding.
In the 1970s-80s, offices were literally stacked with fanfolds—they're the nostalgic relic of the dot-matrix printer era, and some people still prefer them for archival documents because they're compact and durable.
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