“… but above all, Sir Anthony, she should be mistress of orthodoxy, that she might not mis-spell, and mis-pronounce words so shamefully as girls usually do; and likewise that she might reprehend the true meaning of what she is saying.”

Mrs Malaprop, The Rivals by Richard Brinsley Sheridan, 1775

Malaprop; malapropism [from the French mal à propos meaning ‘inopportunely’ or ‘at the wrong moment’.]:

Sheridan wasn’t the first playwright to exploit the misuse of a word for one which sounds similar for comic effect (Shakespeare used it before him), but it is Sheridan’s creation that has famously given her name to the phenomenon. A useful weapon in the arsenal of the comedy writer perhaps, but be careful not to let one slip in unnoticed, as the effect may not be what you were expecting or hoping for. Couldn’t happen, I hear you say! Don’t be so sure. How about this gem which popped up in a letter from a professional correspondent assuring the recipient that they were happy to make an offer as a jester of goodwill?? I still chuckle every time I think of it.

And that’s what you need to keep in mind. If you are sending out a pitch letter or sample manuscript to an agent or, you want them to remember you as an amazingly talented writer, not as someone who can’t tell their ‘jesters’ from their ‘gestures’. Equally, if you are self-publishing, you do not want a reputation amongst your readers for comedy, unless, of course, you are intentionally writing comedy!

My advice?

Obviously, a good copy editor will sort out all such clownish behaviour on the part of your manuscript pretty quickly, but, basically, I’m with Mrs M. on this one: be a master or mistress of orthography so that everyone can comprehend the true meaning of what you are saying – it may save much embarrassment at a later stage.