As you dive into the English language, you’ll probably come across some idioms about knowledge. These are helpful for talking about what you know (or don’t know) and how you use your mind to think wisely and come up with ideas.
It can be hard to know what idioms mean without learning the definition of each one individually, so in this list of knowledge idioms we have included an explanation and example sentence with each one.
Will knowing these expressions make you any wiser? Maybe a little! So let’s take a look.
Must-know idioms about knowledge
Common knowledge
Common knowledge refers to data or information that is broadly acknowledged and accepted by the majority. This idiom about knowledge is used to convey the idea that certain facts are widely understood.
“It’s common knowledge that the Earth revolves around the sun.”
“It’s common knowledge that Jeremy and Pia are dating.”
Know something by heart
When you know something by heart, it means that you’ve memorized it flawlessly to the point that you don’t need to consciously recall it.
“After practicing her speech multiple times, she knew it by heart.”
The origin of this idiom can be traced to the concept of learning something ‘by rote,’ where material is committed to memory through repetition.
This can also be used as a learning idiom; we can refer to learning something by heart to describe the process of committing something to memory.
Knowledge is power
The proverb knowledge is power conveys the idea that the more you know, the more you can control.
For example, in business negotiations, having comprehensive knowledge of the subject matter gives you an advantage and the power to make informed decisions.
“Make sure you go over all the notes thoroughly before the meeting. Knowledge is power, after all.”
A lightbulb moment
You’ll sometimes see a lightbulb used to represent a moment of inspiration or a new idea coming to mind.
This imagery is often associated with Thomas Edison, but it was actually first used in cartoons in the 1930s.
In any case, a lightbulb moment is a moment of sudden inspiration or revelation.
“I was really struggling to think of ideas for my son’s birthday present, but then I had a lightbulb moment.”
Get your thinking cap on
When told to get your thinking cap on, you should start giving some serious thought to the situation or problem. This thinking idiom often requires you to use your knowledge to work out a solution.
“Get your thinking caps on, class! It’s time to solve some math problems.”
This is one of many idioms with items of clothing that have an unrelated meaning.
Put two and two together
Putting two and two together means using logical reasoning to solve a problem or draw a conclusion. It may mean connecting two pieces of information together to reach a reasonable conclusion.
“When I saw the muddy footprints and the empty cookie jar, I put two and two together and realized my kids had been snacking.”
Expanding on this idiom about knowledge, to put two and two together and get five is to come to the wrong conclusion based on the evidence available.
“I don’t want to talk about this until you have clearer evidence. It sounds like you’re putting two and two together and getting five.”
Know the ropes
When you know the ropes, you possess a strong understanding of a process or task. This knowledge idiom is believed to have originated from the days of sailing ships when proficiency in handling ropes and rigging was crucial.
“After working at her new job for a month, she finally knew the ropes and could handle her tasks independently.”
This is another of these English idioms about knowledge where you could substitute ‘learn’ for ‘know’ to describe the process rather than the outcome.
“It’s Suzy’s first day at this school. Which of the students can help her learn the ropes?”
You’ll often hear these idioms in a business context.
Can’t make heads or tails of it
The phrase can’t make heads or tails of it is used when something is too complex or confusing to understand.
“I can’t make heads or tails of these instructions for assembling the furniture.”
A slight variation is ‘heads nor tails’.
Know a trick or two
When someone knows a trick or two, they possess some clever strategies, tactics, or techniques to handle a particular situation.
“As a seasoned baker, she knows a trick or two when it comes to making the perfect loaf of bread.”
“He speaks seven languages, so I’m sure he knows a trick or two when it comes to learning English.”
Brush up on
To brush up on something means to revisit and refresh your knowledge or skills in a particular area.
“I need to brush up on my French before my trip to Paris.”
This could be used as a school idiom to describe what students do before an exam, too.
Know something inside out
To know something inside out means to have a thorough and complete understanding of a subject or topic.
“As a professional mechanic, he knows car engines inside out.”
Know something like the back of your hand
Along a similar theme, to know something like the back of your hand means having an intimate and detailed knowledge of something or being incredibly familiar with it.
“I know this city like the back of my hand, said the taxi driver.”
“Jimmy knows this warehouse like the back of his hand. He can find anything without needing to check the computer.”
Two heads are better than one
The idiom two heads are better than one implies that collaboration and pooling of knowledge can yield better outcomes than one person working alone.
“Let’s work together on this project – after all, two heads are better than one.”
This Biblical idiom appears in the book of Ecclesiastes and was used in English literature by John Heywood in the 16th century.
Mind-blowing
The next of our phrases related to knowledge is a more recent addition to the language. It was originally used in the 1960s to describe psychedelic experiences.
If something is extremely impressive, surprising, or difficult to comprehend, you could describe it as mind-blowing.
“The special effects in that movie were mind-blowing!”
Pick someone’s brain
When you pick someone’s brain, you seek advice or information from someone who is knowledgeable about the topic in question, often an expert in a particular field.
“Can I pick your brain about the best marketing strategies for our new product?”
You can find some more idioms with parts of the body in our separate article.
A walking encyclopedia
A person described as a walking encyclopedia is someone who possesses a broad and impressive knowledge of diverse subjects.
“My grandfather is a walking encyclopedia – he knows something about almost every subject you can think of.”
This knowledgeable expression is a fun one to visualize – an encyclopedia with legs walking around, sharing information with everyone!
More wisdom and knowledge idioms
Off the top of your head
Something said or recalled off the top of your head is done quickly and without much careful consideration. It’s something you know or work out instinctively, without deep thought or calculation.
“Off the top of my head, I’d say there are about 30 people attending the event.”
You can use this knowledge idiom in a negative sense too, to say that you can’t recall something without checking.
“You can’t expect me to know all these sales figures off the top of my head.”
Check out some more head idioms about knowledge, thinking, decisions, and more.
None the wiser
This wisdom idiom is more about lack of knowledge. When you are none the wiser about something, you are completely unaware of it.
“I’m not supposed to have friends over while my parents are out, but they’ll be none the wiser.”
It could also mean that you still can’t understand something, even after being given information about it.
“I gave my husband the instruction manual for the lawnmower so he could fix it, but he’s none the wiser.”
Get wise to
To get wise to someone or something means to become aware of them or it; usually involving bad behavior or something suspicious or illicit.
“I can’t believe our teacher got wise to us passing notes in class.”
You can also be wise to someone or something, meaning you are already aware of them or it.
“He’s been wise to you for longer than you realize.”
A pearl of wisdom
Here’s a lovely idiom about wisdom. A pearl of wisdom is something very wise or helpful that someone says, usually in the form of advice.
“My grandmother was always offering pearls of wisdom to the people in her life.”
Be careful though, because sometimes this expression is used sarcastically.
“Thanks for that pearl of wisdom Dave, now how about you actually come and help me?”
Out of the loop
Being out of the loop signifies a lack of awareness or information about a specific subject or circumstance.
“I’ve been on vacation for two weeks, so I’m out of the loop on the latest office gossip.”
You can, conversely, be in the loop, meaning you are well-informed and knowledgeable about the latest information and most recent developments on a topic.
“Please make sure Selina is kept in the loop about any developments on this matter.”
Ring a bell
When something rings a bell, it seems familiar or reminds you of something previously heard or experienced.
“Does the name Estelle Rigby ring a bell?”
“It rings a bell, but I can’t quite recall why.”
Up to speed
The next of our idioms about knowledge could also be considered a fast idiom, as it has a couple of definitions.
One meaning of being up to speed is that you have reached the desired pace while in motion, whether on foot or in a vehicle.
“It takes a while to get this car up to speed.”
In a more idiomatic sense, though, it means you are completely informed or up-to-date about a specific subject or situation, knowing all the latest information.
“After doing my homework, I’m up to speed on the topic for tomorrow’s test.”
Wrap your head around
Here’s another of these idioms about knowledge that is often used in a negative context when you are struggling to comprehend or understand a topic.
When you wrap your head around something, it means that you comprehend or are coming to understand a complex or challenging concept.
So when you are having trouble understanding something, you can say that you can’t wrap your head around it.
“I’m still trying to wrap my head around the new software we’re using at work.”
“I’ve spent hours trying to learn these phrases for my French test, but I can’t wrap my head around them.”
To the best of my knowledge
The expression to the best of my knowledge is used when the speaker believes the information they are providing is accurate, to their understanding.
It may also act as a disclaimer to acknowledge there may be additional information that the speaker is unaware of.
“To the best of my knowledge, the meeting has been rescheduled for next week.”
Another saying with the same meaning is as far as I know.
For all I know
The knowledge idiom for all I know is similar to the phrases described above except it represents a lack of information.
By saying this, the speaker indicates their knowledge of a certain topic or situation is limited and they cannot give a full or accurate answer.
“For all I know, she could have moved to another city.”
Know your stuff
Being acknowledged as someone who knows their stuff means you are well-versed and competent in a specific area or subject. It could mean that others regard you as an expert.
“Our new accountant really knows her stuff – she’s been able to streamline our financial processes in just a few weeks.”
It takes one to know one
The knowledge idiom it takes one to know one implies that a person can identify certain traits in others because they share the same qualities or have the same experiences.
This is often used when referring to negative qualities. It suggests that the person making the criticism is no better than the one they are criticizing.
“My co-worker called me stubborn, but it takes one to know one!”
Know the score
Someone who knows the score is aware of the facts and circumstances surrounding a particular issue or problem, often encompassing its negative aspects.
“He knows the score when it comes to the challenges of running a small business.”
Not know the half of it
If you don’t know the half of it, it means you are not fully aware of the gravity, complexities, or full extent of a situation.
“You think this project is challenging? You don’t know the half of it!”
Drop a knowledge bomb
When you drop a knowledge bomb, you share an impressive, significant, or surprising piece of information that enlightens others.
“I thought I had my career figured out, but then Clive dropped a knowledge bomb that made me reconsider.”
And that’s the end of our list of knowledge idioms.
We hope the examples helped you see how you can use these wise sayings yourself. Did you get any new ideas for how you can make your own language more expressive? Leave a comment below to let us know.
