As the English language has expanded in a million directions, so has the concept of swearing. Robert A. Leonard, professor of forensic linguistics at Hofstra University, says that the most "successful" swear words tend to be the most versatile -- the ones we use in all sorts of situations, regardless of their literal meaning.
"We have curse words center on three main areas," Leonard says. "Sex; death and religion; and effluvia, let's call it. So what are the most iconic curse words in English? You can fill in the blanks for all three. The prototypical curse words have the largest gap between their literal meaning and their situational meaning."
In her research, Mohr said she simplified the divide into two classifications, religious and vulgar, which is reflected in the title of her book. "You can argue forever over what's an invective, what's a curse. But basically, if you look at it historically, they boil down into these two terms that are in my book, the holy and the sh-t."