Until Hillary Clinton came up with the word 'misspeak - when trying to explain away her (false) claim to have landed in Bosnia under sniper-fire - I'd never heard the words 'misspeak', 'mispoke' or 'misstatement' before. And I remember being vaguely amused at the way both she and an Obama aide used the new word to create some quite neat contrasts, which were reported in The Independent as follows:
'"I think that, a minor blip, you know, if I said something that, you know, I say a lot of things - millions of words a day* - so if I misspoke it was just a misstatement," she said.
'But an Obama spokesman, Tommy Vietor, noted she made her claims in a scripted speech. "When you make a false claim that's in your prepared remarks, it's not misspeaking, it's misleading."'
By Mr Vietor's critera, David Cameron can at least invoke in his defence the fact that this was not a 'scripted speech'.
But an even bigger mistake than the PM's gaffe arguably came from the Downing Street 'source' who decided to borrow and use this newly invented word, even though it had been created for such a dubious purpose and did little or no good for Mrs Clinton's reputation.
After all, as it said in The Independent, she was 'well ahead in most polls' at the time but her misspoken words had 'eclipsed coverage of her scheduled appearances and threatened to undercut her foreign policy experience message'.
All of which is to warn Mr Cameron and his aides that, when it comes to explaining away a mistake or misdemeanour, misguided memos can cause miscellaneous mishaps, mistakes, misconceptions and misfortune, not to mention quite serious misgivings about your 'foreign policy experience message'.
* "Millions of words a day"?
Mrs Clinton's claim to have been saying "millions of words a day" was also an example of 'misspeaking'.
Assuming she was working an 18 hour day at the time and spoke continuously during her waking hours at 150 words per minute (i.e. half-way between the speed of conversation and speech-making), 2 million words (i.e. 'millions', plural) would require a speaking rate of 1,852 words per minute.
Or, to put it another way, delivering 2 million words at a more normal speed of 150 words per minute would take 222 hours - i.e. 12 eighteen-hour days of non-stop speaking without pausing for a moment.