Dating back to the seventeenth century, the word used to describe a substance prone to bursting into flames, such as kerosene, was inflammable, the prefix in actually being used to intensify the word flammable. Usually, however, the prefix in is used to negate the word it precedes, just as incapable means not capable. This linguistic ambiguity led to so many catastrophic fires—thanks to people doing things like throwing cigarette butts into vats marked inflammable—that in the 1950s industrial leaders officially changed the word inflammable to flammable to avoid any confusion. Less perilous, but more annoying, is the confusion caused by the word boned. Since the fifteenth century, boned has referred to meat that has had its bones removed, even though the word sounds as if it should mean the bones are still in. As a result, a statement such as “This fish is not boned” is so ambiguous that thinking about it carefully will result in a Zen-like annihilation of the self. Steps were taken in the 1940s to avoid this confusion by inventing the word deboned; many meat packagers, however, continue to use the ambiguous boned, and thus not a few consumers remain not disabused of their confusion.