When loaves of bread bake, they expand in size, sometimes causing one loaf to lean against another. This point of contact, usually soft instead of crusty, is called the kissing-crust, a baking term dating back to at least the early nineteenth century. Although the name sounds delightful, bakers—before the invention of plastic bags—tried to avoid kissing-crusts because their softness, compared to the rest of the loaf, made them susceptible to mould and burrowing insects. Incidentally, the word kiss, which probably originated as an imitation of the sound of a kiss, dates back in English more than a thousand years; since then, of course, other words have also been used to mean kiss, including the fourteenth century’s beslobber and dab, the sixteenth century’s smack and buss, the seventeenth century’s neb, osculate, and suaviate, and the early nineteenth century’s smack. As well, since the mid eighteenth century, X has been used in love letters to mean kisses.