Unsplash/National Library of MedicineWe use certain phrases so often in everyday conversation that we rarely stop to think about where they came from. But behind many of these seemingly harmless expressions lie origins that are much darker than expected—rooted in violence, punishment, disease, or superstition. From executions to slavery, from medieval medicine to the horrors of war, some of the language we use every day has unsettling beginnings. Once you know where they came from, you might find it hard to hear them the same way again. These phrases might be part of our everyday, but where they came from will blow your mind.
Biting the bullet
Today, this phrase means to endure something painful or unpleasant with courage, but the original reference was brutally literal. Before anaesthetics were widely available, especially on the battlefield, injured soldiers needing emergency surgery would be given a bullet to bite down on to manage the pain and avoid screaming. It helped prevent jaw injuries and gave them something, anything, to focus on as bones were sawed and wounds cauterised.
This practice was especially common during the American Civil War and in earlier centuries when field hospitals were chaotic, unsterile places. The phrase survives today as a metaphor, but its roots are soaked in blood, pain, and desperation.
Rule of thumb
We use this to refer to a rough estimate or guideline, but one often-cited origin is chilling. It’s believed by some to have come from an 18th-century English common law that supposedly allowed a man to beat his wife with a stick no thicker than his thumb.
While the law itself may not have formally existed as written, the idea reflects real societal attitudes toward domestic violence during that time. The phrase became tainted by association and is still controversial. Even if the exact legal origin is debated, the fact that it’s linked in popular memory to violence is unsettling enough.
Saved by the bell
Today, this expression is used when someone narrowly escapes trouble—like a school bell ringing at the end of a difficult exam. But the phrase’s original meaning was much more macabre.
In the 17th and 18th centuries, the fear of being buried alive was real. Medical science wasn’t advanced, and premature burials happened more often than you might expect. As a precaution, a string would be tied to a person’s hand inside the coffin, connected to a bell above ground. If they woke up underground, they could ring for help—hence, being literally “saved by the bell.”
Some cemeteries even employed night watchmen to listen for the sound of ringing. The anxiety around premature burial was so widespread that safety coffins became a niche industry.
Blood is thicker than water
This is used to suggest that family relationships are stronger than any other bond. But many historians believe the original saying was quite the opposite: “The blood of the covenant is thicker than the water of the womb.” That version implies that chosen bonds—like those formed in battle or loyalty—are more meaningful than family ties.
Over time, the quote was shortened and its meaning flipped, but the original message challenged the idea that family must always come first. Instead, it emphasised loyalty forged through experience, not birth.
Going postal
This now means to lose your temper in a sudden, extreme way—often in a workplace setting. But the term originated in the United States in the late 1980s and early ’90s after a string of mass shootings carried out by postal workers who had reached breaking point.
These tragic incidents sparked national conversations about stress, mental health, and workplace violence. The fact that this phrase has become a casual slang term is a stark reminder of how desensitised we can become to very real and devastating events.
Pulling someone’s leg
Used now to mean joking or teasing, this phrase may have come from something darker. One theory suggests it dates back to 18th-century London, where criminals would trip passersby by pulling their legs—either to mug them or set them up for a fall.
Another, even grimmer theory, links it to hangings, where friends or family members would pull on the legs of those being executed to speed up the process and reduce suffering. While there’s no definitive proof of either origin, both are a far cry from the cheeky way we use it today.
Mad as a hatter
Thanks to Lewis Carroll’s “Alice in Wonderland,” we all know the eccentric Mad Hatter. But this phrase has roots in a real occupational hazard. In the 18th and 19th centuries, hat makers used mercury nitrate during the felt-making process. Prolonged exposure to mercury vapour caused mercury poisoning—leading to tremors, hallucinations, slurred speech, and erratic behaviour.
These symptoms became so common among hatters that the phrase “mad as a hatter” entered everyday language. What was once a sign of industrial poisoning is now tossed around as a harmless character quirk.
Skeletons in the closet
Most people use this phrase to refer to a hidden secret or past shame. But in 18th and 19th-century Britain, the expression had a disturbingly literal side. Medical schools often struggled to obtain cadavers for teaching and dissection due to strict laws and public outrage.
As a result, skeletons used for study were sometimes obtained illegally—from grave robbers or unclaimed corpses—and hidden to avoid legal trouble. So a doctor might actually have had a skeleton stashed in a locked cabinet or closet, both as a teaching aid and as a secret liability.
Let the cat out of the bag
Meaning to reveal a secret, this phrase may trace its origins back to medieval markets. Farmers would sell piglets in sacks, but a dishonest seller might substitute a less valuable animal—like a stray cat. If the buyer opened the bag to inspect the goods, they’d expose the trick—literally letting the cat out of the bag.
It’s a reminder of how language reflects common scams and anxieties of the time—and how those concerns often made their way into metaphor.
Caught red-handed
Used to describe being caught in the act, this phrase dates back to 15th-century Scotland. It originally referred to someone apprehended with blood on their hands after a murder or poaching.
It became a legal term used in courts to establish undeniable guilt. The phrase later took on a broader meaning, but the original image—blood on your hands and no way to explain it—is still one of the most vivid origins in the list.
Breaking the ice
Now used to describe easing tension in social situations, this phrase once had a very practical purpose. In the days of sea trade, ports would freeze in winter, and ships couldn’t move. Small boats were sent out first to break the ice and clear a path for larger vessels.
The expression became a metaphor for making the first move in challenging situations—be it in business, diplomacy, or conversation. What was once about literal icebreaking has become an everyday social skill.
No room to swing a cat
Used to describe tight, cramped conditions, this phrase likely refers not to a literal animal but to the “cat o’ nine tails”—a multi-tailed whip used for corporal punishment in the navy. Below deck, space was often too limited to use the whip without hitting walls or beams.
It’s easy to misunderstand the phrase today, but its roots lie in maritime discipline—where brutal floggings were a routine form of enforcement. That such a violent practice inspired a casual idiom speaks volumes about what was once considered normal.
Give the cold shoulder
Giving someone the cold shoulder now means ignoring or dismissing them. In medieval Britain, it was said that when guests had overstayed their welcome, hosts would offer a cold shoulder of mutton rather than a hot meal. It was a subtle signal that the hospitality was over.
Whether this story is apocryphal or not, the phrase stuck. Today it’s more likely to refer to passive-aggressive behaviour than an actual meal, but the message is just as chilly.
Deadline
These days, a deadline is just a due date. But during the American Civil War, it was far more sinister. In Confederate prisoner-of-war camps like Andersonville, a line was drawn several feet inside the perimeter fence. Any prisoner who crossed it, even accidentally, could be shot on sight.
It was called the “dead line” for good reason. Crossing it meant death, no questions asked. The modern use of the word retains none of that lethal finality—but the origin is a chilling one.
