Like any language, English contains a vast wealth of idioms¹, proverbs, and collocations², which we use every day without giving them much thought - set expressions whose meaning we know.

However, when it comes time to use them in writing, they can cause some confusion, because we suddenly realise that we know what the phrase means and what it sounds like, we don't really know which words it's made up of. Like misheard song lyrics give us mondegreens, misheard words in ordinary speech give us 'eggcorns', named after a 'slip of the ear' in which someone thought acorns were, in fact, 'egg corns'. Often, archaic words will be preserved only in one set expression, as in 'kith and kin' - everyone knows that this means your nearest and dearest, and the fact that 'kin' means your family can be guessed at from the phrase 'next of kin'. 'Kith', however, is a Middle English word for friends or close neighbours that has long fallen out of general use.

The phrase is still usually rendered correctly, because there's not much you can confuse 'kith' with³ - but many other expressions contain words that sound the same as other words, and often, one of the words it could be has fallen out of fashion, while the other is more commonly used. In a tragic case of mistaken identities, the poor homophone is pressed into service, even if it doesn't make sense. After all, we know what the phrase means, so why worry about why it means it?

Eh Eh, Sir!

Batten down the hatches is often misrendered as batter down the hatches.

It's fascinating that changing a single letter could change the literal meaning of a phrase to its opposite, while its meaning as an idiom is still understood. To 'batter' something down is to break it through brute force. A batten is a strip of wood used to reinforce something or cover gaps. Literally, the phrase 'to batten down the hatches' means making sure that any openings on a ship are securely covered when bad weather is expected; figuratively, strengthening one's defences in expectation of difficult times.

Bated breath is often misrendered as baited breath.

The confusion here may stem from the fact that 'bated' isn't really a word we use outside that one expression⁴ - it's a contraction of 'abated', meaning reduced or lessened in force - that is, a student waiting for that all-important exam result with bated breath has almost stopped breathing out of nervosity, that little gasp-and-hold breath when you see something exciting. Figuratively, one hopes, because it does take quite a while to correct all those papers... The first known use of the phrase in writing occurs in The Merchant of Venice - so blame William Shakespeare for the confusion; he was always willing to drop a few letters if it helped the metre.

Geoffrey Taylor deliberately misused the phrase in 'Cruel Clever Cat', to show what 'baited breath' would be:

Sally, having swallowed cheese,
Directs down holes the scented breeze,
Enticing thus with baited breath
Nice mice to an untimely death.

Eke out is often misrendered as eek out.

Once those mice come out of their holes they'll certainly go 'eek'! But cats without cheese breath will just have to eke out a living hunting them down the old-fashioned way. 'Eke' is another word that's no longer heard by itself, just in conjunction with 'out'. Originally, it meant 'to increase', but the meaning has changed to mean making do or struggling to get by with what little is available, usually through hard work and strict rationing to make it last.

Wet your whistle is often misrendered as whet your whistle.

This isn't the same as 'whetting your appetite', making it sharper like an axe being ground on a whetstone. It's for when you're quite thirsty enough already - to wet one's whistle means to take a drink, 'whistle' being a slang term for the throat or, in a less literal sense, the voice. Talking or singing (or whistling) with a dry mouth and throat is less than pleasant and won't make you sound your best.

This expression has been around for quite a while - its earliest known written use is in the Towneley Mysteries, a series of religious plays from Wakefield, West Yorkshire, which were performed in the 14th and 15th Centuries.

As sharp as thystylle, as rugh as a brere,
She is browyd lyke a brystylle, with a sowre, loten, chore;
Had she oones wett hyr whystyll
she couth syng fulle clere hyr pater noster.

Back-pedal is often misrendered as back-peddle.

No, this doesn't mean you changed your mind and decide to sell something back to the vendor you bought it from - we have the lovely expression 'buyer's remorse' for that. Taken literally, the phrase means turning the pedals a bicycle backwards to brake - or, in the days before modern bicycle gears, even to make it go backwards. It's now used as a metaphor for changing your mind or realising you've stated your opinion too strongly or extremely, and seeking to rectify it by hastily adding that you didn't mean it quite in that way - heh heh, simple misunderstanding, didn't mean to offend you... In sports like boxing, you 'backpedal' more literally, taking small, fast steps backward - also to avoid confrontation.

Poring over is often misrendered as pouring over.

When you're closeted in your study, reading, you might be so absorbed in your books that you reach for the pitcher and accidentally pour water over one of them rather than into your glass because you can't take your eyes off that fascinating paragraph. Barring such accidents, however, what you're doing is poring over your books. 'Pore' means to study intently, to stare at, or to ponder, which might mean a subsequent outpouring of wisdom on your part, but usually doesn't involve getting anything wet.

Beyond the pale is often misrendered as beyond the pail.

This expression, likewise, has nothing to do with getting anything wet. It does not mean 'my bucket runneth over'! Going 'beyond the pale' now means going past the bounds of what is socially or morally acceptable. A pale is a long, sharpened stake - the kind you'd use to impale someone, or to build a palisade, but can also refer to the fence itself, or the area enclosed in it. It is from the latter meaning that we get this expression; the word 'pale' was being used figuratively as early as the 14th Century. Medieval England had two large Pales, which were strictly bounded, but not physically enclosed - the Pale of Calais was the last part of France to remain in English hands after the Hundred Years' War, while the English Pale, extending some 15km beyond the city walls⁵ of Dublin, was the only part of Ireland under English jurisdiction. The Pale of Settlement in Russia is a more modern example, only dissolved after the revolution in 1917, and marked the area along the empire's western border in which Jews were allowed to live.

An early example of the word 'pale' used in a figurative sense occurs in one of the first books to be printed in English, The Golden Legende, William Caxton's translation of the Legenda Sanctorum, in which it is used to mean a field of study or a sphere of interest. The complete phrase was first used in writing in 1657, in John Harington's poem The History of Polindor and Flostella, where two lovers 'Both Dove-like roved forth beyond the pale to planted Myrtle-walk'. This turns out not to be a good idea, as they are soon beset by robbers in the wild, untamed area beyond the gardens of the safe country lodge - a rather more literal going beyond the pale. In 1837, Charles Dickens used the phrase as we know it now in The Pickwick Papers, when Mr Pott proclaims to Mr Slurk 'I look upon you, sir, as a man who has placed himself beyond the pale of society, by his most audacious, disgraceful, and abominable public conduct. I view you, sir, personally and politically, in no other light than as a most unparalleled and unmitigated viper.'

Shoo-in is often misrendered as shoe-in.

A popular misconception is that this refers to a figurative salesman who, once he's got a shoe in the door, is guaranteed to sell you something because you can't get rid of him - a rather elaborate bit of folk etymology. It certainly is a term for a sure winner who won't even have to make much of an effort, but it comes from horse-racing, where it was popular in the early 20th Century. 'Shoo' means to chase something away using gestures or one's voice, and a horse that was a 'shoo-in' was either considered fast enough anyway not to require much work from the jockey, or running a rigged race in which it would be enough to move the animal in roughly the right direction to let it win.

Free rein is often misrendered as free reign.

This is another one from the horsey world, and is very often confused by non-equestrians, especially as the phrase 'free reign' sounds quite plausible. Giving a horse free rein means not holding it back, letting it move its head (and so, itself) as it wishes. Giving someone free rein is subtly different from handing them the reins, that is, letting them take over, because the possibility of bringing them back under control is still there.

Straitjacket is often misrendered as straightjacket.

It's neither intended to make you sit up straight nor to scare you straight, and the wearer's arms are usually twisted up like a pretzel. The 'strait' in 'straitjacket' is the same as in 'dire straits', or, for that matter, the Strait of Gibraltar. Strait is an old-fashioned word for 'narrow' or 'confined', or, in a figurative sense, 'strict' or 'righteous'. The straitjacket was meant to combine both, confining a mental patient for his own good.

One fell swoop is often misrendered as one foul swoop.

While the word 'fell' has many uses, both as a verb and a noun, its meaning as an adjective, cruel, lethal, sinister, has fallen out of use, except in poetry and this one phrase.

Again, its earliest recorded use comes from a Shakespeare play:

Ross: Your castle is surprised; your wife and babes
Savagely slaughter'd.'
[...]
Macduff: All my pretty ones?
Did you say all? O hell-kite! All?
What, all my pretty chickens and their dam
At one fell swoop?
- Macbeth, Act 4, Scene 3

Here, 'swoop' is being used as part of the metaphor of a bird of prey killing chickens. The set expression 'at one fell swoop' has since entered the English language to mean anything that happens unpredictably and all at once.

Hem and haw is often misrendered as hum and hah.

Mmmmhmmmmhmmmhmh - a-hah! Is that really the sound of someone being indecisive? Actually, it very nearly is, but someone unable to make up their mind uses a set pair of noises to express this. A 'hem' is that little cough or clearing of the throat used by someone who's still thinking about what to say - 'to utter a hem' gives us the written 'ahem'. It also means 'to hesitate in speech'. 'Haw', on the other hand, is a term for that little noise somebody who's nervous uses as a filler when talking, and as a verb, means 'to fumble in speaking'. And so, uh, dear reader, hemming and, hm, hawing is talking hesitantly, and, er, haltingly, because you're not quite, um, sure what to say... Or any other form of obvious dithering, for that matter.

Mother lode is often misrendered as mother load.

Discovering that mummy's backpack is full of chocolate might be finding the mother load. In any other case where you've found a lot of something valuable, you've hit the mother lode. This is a metaphorical use of the mining term 'mother lode', meaning a large and relatively pure vein of gold or silver, from which smaller deposits might have broken off.

Damp squib is often misrendered as damp squid.

Squids work better when they're kept moist. Squibs don't. The latter are small explosive charges with no tentacles at all that are used for special effects, propulsion, and anywhere else you just happen to need a small explosive charge. Unless, of course, they get wet, in which case, the powder won't ignite⁶. They won't have the intended effect, and can make you look quite ridiculous. The same is true of writing 'damp squid' when you mean 'damp squib'.

Hear hear is often misrendered as here here.

Where where? This expression of approval simply means 'listen to what that person is saying, it's quite correct!' and has nothing to do with a specific location. A shortened form of 'Hear him! Hear him!', it's been 'the regular form of cheering in the House of Commons' since the 17th Century. Like many other expressions, this is currently misused more than used correctly on the internet, which just goes to show that you shouldn't let the popular vote decide what's the right way to spell something. Hear hear!