The earlier word for it in English, covering both written and spoken defamation, was slander, and it carried a powerful punch. This can't be said of the Latin-derived libel, which began life as a mere diminutive, a libellus being a little book. Then it was a statement or a notice stuck on a wall. It was also a pamphlet, or squib.
Pamphleteers have a tendency to be scurrilous, and walls invite self-expression by those with grudges, even if all they want to say is Fatty Roberts is a Fool, so it is easy to see how the word came to have the exclusive legal meaning it has now. But as I say, it is not quite the word we need, and is in danger of being laughed out of court.
Unfortunately slander won't do as a substitute, now that it has also acquired an exclusive meaning, and relates only to defamation uttered by word of mouth, which is not, I understand, a criminal offence. In the 18th century, when it had been going strong for 400 years, slander could still be used for written statements (there is a reference in the Junius Letters to 'slanderous tongues and pens'). Since 1952, however, the distinction between libel and slander - the one written, the other spoken - has become blurred again: things said on television or radio can be libellous, too. It's a bit of a mess, really.
Meanwhile, if anyone is seriously rude about me I shall accuse them of calumny. This has the advantage of being harder to say, and does not, as libel does, invite the response: 'You must be joking.'Reuse content