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Eight ingenious idioms and their origins

Why do we “let the cat out of the bag” or try to “go the whole nine yards”? And why is it ill advised to “look a gift horse in the mouth”?

In Word of Mouth, the writer behind the , Paul Anthony Jones, discusses the origins of common idioms – phrases that have taken on a meaning different from that of the individual words themselves.

1. Let the cat out of the bag

Meaning: To disclose a secret, normally without meaning to.

Origin: Paul Anthony Jones explains how the phrase originates from the days when you would go down to an agricultural fair and buy “a prize piglet that would get put in a sack and you’d take it back home and when you open the sack again you’d find it was just a stray cat, and you’d been had.”

Example: “The gift for my Mum was meant to be a surprise but Dad let the cat out of the bag by pointing out the parcel in the post.”

2. Don’t look a gift horse in the mouth

Meaning: Don't find fault with something that you’ve been given as a gift.

Origin: A horse’s value is determined by its age, and this can be worked out by looking in its mouth: a horse’s teeth get longer as it gets older. To look a horse you’ve been given in the mouth is therefore to assess its value and, quite frankly, on the rude side. This proverb first appeared in print in 1546 when John Heywood wrote: “No man ought to look a geuen [given] hors [horse] in the mouth.”

Example: “Thanks for my birthday present! Of course I’d rather the jumper wasn’t yellow, but I won’t look a gift horse in the mouth.”

3. The whole nine yards

Meaning: Everything there is, or all the way.

Origin: This is an idiom, Paul says, where “there are plenty of ideas” about its origins. Could it be the amount of fabric needed to make a kilt or a nun’s habit? The length of a WWII fighter pilot’s ammunition? The length of the hangman’s noose?

This cat doesn't like bags.
Horses' teeth get longer as they get older.

Luckily, Dr Laura Wright in Word of Mouth went the whole nine yards to get us the answer: in 1885 a newspaper in Indiana ran a story about a judge’s oversized shirt with the quote, “she’s put the whole nine yards in to one shirt”. The phrase carried across the pond and has stayed in circulation ever since.

Raising one's hackles originally came from the quills on the back of a cockerel, which stand up when the bird gets angry.

Example: “Now we’ve spent this much on the wedding we may as well go the whole nine yards and get a horse drawn carriage.”

4. Over the moon

Meaning: To be ecstatically happy.

Origin: The origin of this one comes from the popular 16th century nursery rhyme, Hey Diddle Diddle: “Hey diddle diddle, the cat and the fiddle, the cow jumped over the moon. The little dog laughed to see such fun and the dish ran away with the spoon.”

Example: “We’ve won the lottery! I’m over the moon.”

5. Raise one’s hackles

Meaning: To greatly irritate, annoy, or aggravate someone.

Origin: Paul explains that the word hackle has evolved to mean “the fur on the back of a cat” but, he says, “if you look it up in the dictionary it originally referred to the quills on the back of a cockerel and these will be pushed up when the cockerel gets angry or enraged.”

Example: “You shouldn’t have told Terry his tagine needed more salt – you’ve really raised his hackles.”

6. Bite the bullet

Meaning: To decide to do something difficult or unpleasant.

Origin: It could be that this phrase sprung from the battlefield, at a time preceding anaesthesia or painkillers. For a patient undergoing surgery, a bullet is said to have been an impromptu wartime alternative to biting down on a piece of wood.

Example: “I’m going to bite the bullet and tell the kids the TV is broken.”

7. Caught red-handed

Meaning: To be caught in the act of doing something wrong.

Origin: An old law meant that the only way a person could be convicted of poaching is if he was caught with the animal’s blood on his hands. The first written mention of “red hand” is in the Scottish Acts of Parliament of James I, from 1432: “That the offender be taken reid [red] hand.”

Example: “Ha! I knew my toilet paper was disappearing and now I've caught you red-handed stealing another loo roll from my cupboard!”

8. Don’t throw the baby out with the bath water

Meaning: Don’t get rid of something valuable or good along with the bad.

Origin: This was originally a German proverb from the 1500s, when the whole household would have shared the same bathwater. The head of the house would have bathed first, followed by the rest of the men, then the women, the children – and lastly the baby. By this point the water would have been dark with dirt and a baby could accidentally be thrown out with the filthy water!

Example: “Don’t start the whole essay from scratch and throw the baby out with the bath water – there are lots of good ideas in there worth keeping.”

Being 'over the moon' originates from the nursery rhyme Hey Diddle Diddle.

Learn more about the meanings behind some of our most well-used idioms in Radio 4's Word of Mouth on Haggard Hawks.

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