IdiomS in a nutshell

#fffff Idiom: a manner of speaking that is natural to native speakers of a language
Every language has its own collection of wise sayings. They offer advice about how to live and also transfer some underlying ideas, principles and values of a given culture / society. These sayings are called "idioms" - or proverbs if they are longer. These combinations of words have (rarely complete sentences) a "figurative meaning" meaning, they basically work with "pictures".
This List of commonly used idioms and sayings (in everyday conversational English), can help to speak English by learning English idiomatic expressions. This is a list, which contains exactly 66 of the most commonly used idioms and their meaning.
Smart Idioms
A hot potato
Speak of an issue (mostly current) which many people are talking about and which is usually disputed
A penny for your thoughts
A way of asking what someone is thinking
Actions speak louder than words
People's intentions can be judged better by what they do than what they say.
Add insult to injury
To further a loss with mockery or indignity; to worsen an unfavorable situation.
An arm and a leg
Very expensive or costly. A large amount of money.
At the drop of a hat
Meaning: without any hesitation; instantly.
Back to the drawing board
When an attempt fails and it's time to start all over.
Ball is in your court
It is up to you to make the next decision or step
Barking up the wrong tree
Looking in the wrong place. Accusing the wrong person
Be glad to see the back of
Be happy when a person leaves.
Beat around the bush
Avoiding the main topic. Not speaking directly about the issue.
Best of both worlds
Meaning: All the advantages.
Best thing since sliced bread
A good invention or innovation. A good idea or plan.
Bite off more than you can chew
To take on a task that is way to big.
Blessing in disguise
Something good that isn't recognized at first.
Burn the midnight oil
To work late into the night, alluding to the time before electric lighting.
Can't judge a book by its cover
Cannot judge something primarily on appearance.
Caught between two stools
When someone finds it difficult to choose between two alternatives.
Costs an arm and a leg
This idiom is used when something is very expensive.
Cross that bridge when you come to it
Deal with a problem if and when it becomes necessary, not before.
Cry over spilt milk
When you complain about a loss from the past.
Curiosity killed the cat
Being Inquisitive can lead you into an unpleasant situation.
Cut corners
When something is done badly to save money.
Cut the mustard [possibly derived from "cut the muster"]
To succeed; to come up to expectations; adequate enough to compete or participate
Devil's Advocate
To present a counter argument
Don't count your chickens before the eggs have hatched
This idiom is used to express "Don't make plans for something that might not happen".
Don't give up the day job
You are not very good at something. You could definitely not do it professionally.
Don't put all your eggs in one basket
Do not put all your resources in one possibility.
Drastic times call for drastic measures
When you are extremely desperate you need to take drastic actions.
Elvis has left the building
The show has come to an end. It's all over.
Every cloud has a silver lining
Be optimistic, even difficult times will lead to better days.
Far cry from
Very different from.
Feel a bit under the weather
Meaning: Feeling slightly ill.
Give the benefit of the doubt
Believe someone's statement, without proof.
Hear it on the grapevine
This idiom means 'to hear rumors' about something or someone.
Hit the nail on the head
Do or say something exactly right
Hit the sack / sheets / hay
To go to bed.
In the heat of the moment
Overwhelmed by what is happening in the moment.
It takes two to tango
Actions or communications need more than one person
Jump on the bandwagon
Join a popular trend or activity.
Keep something at bay
Keep something away.
Kill two birds with one stone
This idiom means, to accomplish two different things at the same time.
Last straw
The final problem in a series of problems.
Let sleeping dogs lie
Meaning - do not disturb a situation as it is - since it would result in trouble or complications.
Let the cat out of the bag
To share information that was previously concealed
Make a long story short
Come to the point - leave out details
Method to my madness
An assertion that, despite one's approach seeming random, there actually is structure to it.
Miss the boat
This idiom is used to say that someone missed his or her chance
Not a spark of decency
Meaning: No manners
Not playing with a full deck
Someone who lacks intelligence.
Off one's rocker
Crazy, demented, out of one's mind, in a confused or befuddled state of mind, senile.
On the ball
When someone understands the situation well.
Once in a blue moon
Meaning: Happens very rarely.
Picture paints a thousand words
A visual presentation is far more descriptive than words.
Piece of cake
A job, task or other activity that is easy or simple.
Put wool over other people's eyes
This means to deceive someone into thinking well of them.
See eye to eye
This idiom is used to say that two (or more people) agree on something.
Sit on the fence
This is used when someone does not want to choose or make a decision.
Speak of the devil!
This expression is used when the person you have just been talking about arrives.
Steal someone's thunder
To take the credit for something someone else did.
Take with a grain of salt
This means not to take what someone says too seriously.
Taste of your own medicine
Means that something happens to you, or is done to you, that you have done to someone else
To hear something straight from the horse's mouth
To hear something from the authoritative source.
Whole nine yards
Everything. All of it.
Wouldn't be caught dead
Would never like to do something
Your guess is as good as mine
To have no idea, do not know the answer to a question