Sixfold means six times as much, or multiplied by six. If prices rise sixfold, they become six times what they were — not “six more”, and not “plus six percent”. You can use it as an adjective (a sixfold increase) or as an adverb (sales grew sixfold). It sounds a little more formal than “six times”; you will meet it in news, reports, and science writing more than in the playground. The pattern is the same as twofold, threefold, tenfold: a number plus -fold. Older English used fold this way for “times as many”, and we still do in these compounds, even though fold by itself now mostly means to bend paper. “Increased sixfold” is one of those tidy phrases people trip on: the new amount is six times the old one. If something goes from 2 to 12, that is sixfold.

六倍（的／地）