K

Kangaroo court
When people take the law into their own hands and form courts that are not legal, these are known as kangaroo court.
Keen as mustard
If someone is very enthusiastic, they are as keen as mustard.
Keep abreast
If you keep abreast of things, you stay informed about developments.
Keep at bay
If you keep someone or something at bay, you maintain a safe distance from them.
Keep body and soul together
If you earn enough to cover your basic expenses, but nothing more than that, you earn enough to keep body and soul together.
Keep mum
If you keep mum about something, you keep quiet and don’t tell anyone.
Keep posted
If you keep posted about something, you keep up-to-date with information and developments.
Keep up with the Joneses
People who try to keep up with the Joneses are competitive about material possessions and always try to have the latest and best things.
Keep your chin up
This expression is used to tell someone to have confidence.
Keep your ear to the ground
If you keep your ear to the ground, you try to keep informed about something, especially if there are rumours or uncertainties.
Keep your eye on the ball
If you keep your eye on the ball, you stay alert and pay close attention to what is happening.
Keep your fingers crossed
If you are keeping your fingers crossed, you are hoping for a positive outcome.
Keep your hair on
Keep your hair on is advice telling someone to keep calm and not to over-react or get angry.
Keep your head above water
If you are just managing to survive financially, you are keeping your head above water.
Keep your nose clean
If someone is trying to keep their Nose Clean, they are trying to stay out of trouble by not getting involved in any sort of wrong-doing.
Keep your pecker up
If someone tells you to keep your pecker up, they are telling you not to let your problems get on top of you and to try to be optimistic.
Keep your powder dry
If you keep your powder dry, you act cautiously so as not to damage your chances.
Keep your shirt on!
This idiom is used to tell someone to calm down.
Keep your wig on!
This idiom is used to tell someone to calm down.
Keeping your options open
Is someone’s keeping her or his options open, they aren’t going to restrict themselves or rule out any possible course of action.
Kettle of fish
A pretty or fine kettle of fish is a difficult problem or situation.
Kick away the ladder
If someone kicks away the ladder, they remove something that was supporting or helping someone.
Kick in the teeth
Bad news or a sudden disappointment are a kick in the teeth.
Kick something into the long grass
If an issue or problem is kicked into the long grass, it is pushed aside and hidden in the hope that it will be forgotten or ignored.
Kick the bucket
When someone kicks the bucket, they die.
Kid gloves
If someone is handled with kid gloves, they are given special treatment and handled with great care.
Kill the goose that lays the golden egg
If you kill the goose that lays the golden egg, you ruin something that is very profitable.
Kill two birds with one stone
When you kill two birds with one stone, you resolve two difficulties or matters with a single action.
Kindred spirit
A kindred spirit is someone who feels and thinks the way you do.
Kiss of death
The kiss of death is an action that means failure or ruin for someone, a scheme, a plan, etc.
Kith and kin
Your kith and kin are your family; your next of kin are close relations you nominate to deal with your affairs in the event of your death on a document.
Knee-jerk reaction
A knee-kerk reaction is an instant, instinctive response to a situation.
Knock ‘em dead
‘Knock ‘em dead’ is used as a way of wishing someone luck before they give a performance or have to appear before people, as in an interview, etc. (‘em = them)
Knock your socks off
If something knocks your socks off, it amazes and surprises you, usually in a positive way.
Know full well
When you know full well, you are absolutely sure that you know.
Know the ropes
Someone who is experienced and knows how the system works know the ropes.
Know which side one’s bread is buttered on
If you know which side one’s bread is buttered on, you know where your interests lie and will act accordingly to protect or further them.
Know your onions
If someone is very well-informed about something, they know their onions.
Know your place
A person who knows their place doesn’t try to impose themselves on others.