What is an expletive?

The term "expletive" usually refers to a bad Word, often called a "swear" or a "curse" Word. In many newspapers & magazines, there are codes that do not permit bad language (like the swear Word that begins with F, jokingly called the "F-bomb") to be written, since seeing bad language supposedly might offend someone, or set a bad example for young people. Thus, newspapers will use a euphemism (a polite way of saying something vulgar), or they will just say the person "uttered an expletive."