Twofold, double.
Of two kinds.
A wallet, billfold, or carrying case with a single fold, so that it opens like a book.
A door, window, shutter, or divider consisting of two equal panels hinged together so that it opens by folding the panels against each other.
A sheet of paper or cardboard folded in half along a crease down the center.
A crease or turn that causes something to double back on itself.
triple
three times as great
To make threefold; to triple.
An algebraic variety of dimension 3.
by a factor of three