Forklore: Biscuits, cooked once
Everybody knows that biscotti are cooked twice. Well, in Latin "twice cooked" is bis coctus, the expression from which biscotto comes, but that doesn't mean that when you ask for a biscotto in Italy, you'll get something that has been cooked twice.
The original biscotto certainly was a twice-cooked bread made from barely leavened dough. The second cooking was to dry it out, making a sort of tough cracker that could be taken on journeys, especially by sailors. "Sea biscuits" of this sort are still sold, mostly as emergency or survivalist food.
But by the 14th century or so, biscotto had become the name for any sort of Italian pastry that was small and crisp, whether cooked twice or not. The recent "Grande Enciclopedia Illustrata della Gastronomia" defines the word as "a sweet of small dimensions, basically made from flour, water, sugar and shortening with the eventual addition of eggs and natural flavorings."
In other words, a biscotto is a cookie. In Italy, even savoiardi, the small, elongated cakes we call ladyfingers, are biscotti.
The word biscotto entered our language first in its French form, biscuit. Now you know why in England, both cookies and crackers are called biscuits.
-- Charles Perry