WARNING: This piece contains vulgar language—lots and lots of it—that may be inappropriate for children or the faint of heart.
In 1966, Jess Stein, the editor-in-chief of the major Random House Dictionary of the English Language, told the New York Times about a meeting he convened with the company's editorial and sales staff to discuss the words cunt and fuck. "When I uttered the words there was a shuffling of feet, and a wave of embarrassment went through the room," he said. "That convinced me the words did not belong in the dictionary, though I'm sure I'll be attacked as a prude for the decision."
Stein did not have to wait long to be proven right on the last point: A mere two weeks later, the Times' own book reviewer wrote, "Unfortunately, a stupid prudery has prevented the inclusion of probably the most widely-used word in the English language. The excuse here, no doubt, is 'good taste'; but in a dictionary of this scope and ambition the omission seems dumb and irresponsible."
With the advantage of hindsight, Stein may seem priggish. But dictionary editors throughout history would sympathize. Figuring out how to put sex in the dictionary—which terms to include and how to define them—is actually one of the most challenging tasks we face.
The 1960s actually marked the end of a long drought in the inclusion of sexual terms in dictionaries. The word fuck is first found in a dictionary in 1598, when it was one of five synonyms given to translate the Italian word fottere (the others were jape, sard, swive,and occupy). It is included in several other dictionaries throughout the 17th and 18th centuries (though not in that of Samuel Johnson, who made a conscious decision to keep out such material); Nathan Bailey's major Dictionarium Britannicum of 1730 included the odd note that it was "a term used of a goat," perhaps in an effort to make it seem less offensive. The last general dictionary to include the word was the 1775 New and Complete Dictionary of the English Language by Baptist preacher John Ash; the word is still found in the 1795 edition.
But after that, thanks to the public prudishness that characterized the Victorian era and lasted well beyond it, it was to be 170 years before fuck was again put into a general dictionary: In 1965, the British Penguin English Dictionary included the term, and its entire treatment read, "(vulg) (of males) have sexual intercourse (with)."
One major problem dictionary editors face in defining sexual terms is deciding how explicit to be. Defining coitus as "an act of sexual intercourse" but leaving sexual intercourse undefined, for example (on the grounds that a reader could figure it out from the definitions of sexual and intercourse), would be a problem, not only because it makes the reader do too much page-flipping but also because the definitions probably still won't be sufficiently clear.
Such evasive definitions aren't confined to English dictionaries. In the Oxford Latin Dictionary, the word irrumo is defined "[t]o practise irrumatio on." Great. Irrumatio, less than helpfully, is "[t]he action of an irrumator." We finally learn that an irrumator is "[o]ne who submits to fellatio." And thus, after flipping your way through three different entries, you get a definition that, while described precisely enough (and better than its counterpart in the main Victorian Latin dictionary, "to commit beastly acts"), is completely wrong. An irrumator is the active, not the passive, participant. The real meaning of irrumo is something like "to fuck (someone) in the face, esp. as a way of asserting dominance"; it is frequently found in the locker-room talk of Catullus and also appears in Martial's scurrilous epigrams.
Even when the definitions of sexual terms are clear, they can often omit important aspects of the meaning. Homosexual practices have been notoriously poorly treated until quite recently. There was a controversy earlier this year when conservatives realized that Merriam-Webster had included a definition of marriage reading "the state of being united to a person of the same sex in a relationship like that of a traditional marriage." (This definition had been added years before, and many other dictionaries include similar treatments, but Merriam got singled out anyway.) And marriage is an obvious place to remember to be inclusive; sexual terms are less so. A definition for sixty-nine reading "simultaneous fellatio and cunnilingus by two partners" (from the Random House College Dictionary, an older edition) omits the possibility of a homosexual sixty-nine.