Idioms Beginning With 'U'

U-turn
If a government changes its position radically on an issue, especially when they have promised not to do so, this is a U-turn.
Ugly as a stick
(USA) If someone is as ugly as a stick, they are very ugly indeed.
Ugly duckling
An ugly duckling is a child who shows little promise, but who develops later into a real talent or beauty.
Uncalled for
If someone does something bad and unnecessary without consideration for anothers feelings, what they do is uncalled for.
Uncharted waters
If you're in uncharted waters, you are in a situation that is unfamiliar to you, that you have no experience of and don't know what might happen. ('Unchartered waters' is an incorrect form that is a common mistake.)
Uncle Sam
(USA) Uncle Sam is the government of the USA.
Under a cloud
If someone is suspected of having done something wrong, they are under a cloud.
Under a flag of convenience
If a ship sails under a flag of convenience, it is registered in a country where taxes, etc, are lower than in the country it comes from, so if someone does something under a flag of convenience, they attempt to avoid regulations and taxes by a similar means.
Under false colours
If someone does something under false colours/colors, they pretend to be something they are not in order to deceive people so that they can succeed.
Under fire
If someone is being attacked and cricitised heavily, they are under fire.
Under lock and key
If something is under lock and key, it is stored very securely.
Under someone's heel
If you are under someone's heel, they have complete control over you.
Under the radar
If something slips under the radar, it isn't detected or noticed.
Under the table
Bribes or illegal payments are often described as money under the table.
Under the weather
If you are feeling a bit ill, sad or lack energy, you are under the weather.
Under the wire
(USA) If a person does something under the wire, they do it at the last possible moment.
Under your belt
If you have something under your belt, you have already achieved or experienced it and it will probably be of benefit to you in the future.
Under your breath
If you say something under your breath, you whisper or say it very quietly.
Under your nose
If something happens right in front of you, especially if it is surprising or audacious, it happens under your nose.
Under your skin
If someone gets under your skin, they really annoy you.
Under your thumb
Someone who is manipulated or controlled by another person is under his or her thumb.
Uneasy lies the head that wears the crown
This means that people with serious responsibilities have a heavy burden.
Unwavering loyalty
Unwavering loyalty does not question or doubt the person or issue and supports them completely.
Up a gum tree
(AU) If you're up a gum tree, you're in trouble or a big mess.
Up a river without a paddle
If you up a river without a paddle, you are in an unfortunate situation, unprepared and with none of the resources to remedy the matter.
Up for grabs
If something is up for grabs, it is available and whoever is first or is successful will get it.
Up in the air
If a matter is up in the air, no decision has been made and there is uncertainty about it.
Up sticks
(UK) If you up sticks, you leave somewhere, usually permanently and without warning- he upped sticks and went to work abroad.
Up the ante
If you up the ante, you increase the importance or value of something, especially where there's an element of risk as the term comes from gambling, where it means to increase the stake (the amount of money bet).
Up the creek
If someone or something is up the creek, they are in real trouble. 'Up the creek without a paddle' is an alternative, and 'up shit creek (without a paddle)' is a ruder form.
Up the duff
(UK) If a woman is up the duff, she's pregnant.
Up the spout
(UK) If something has gone up the spout, it has gone wrong or been ruined.
Up the stick
(UK) If a woman is up the stick, she's pregnant.
Up the wall
If someone goes up the wall, they get very angry.
Up the wooden hill
When you go up the wooden hill, you go up the stairs to bed.
Up to scratch
If something doesn't come up to scratch, it doesn't meet the standard required or expected.
Up to snuff
If something isn't up to snuff, it doesn't meet the standard expected.
Up to speed
If you bring someone up to speed, you update them on something.
Up to the eyes
You you are up to your eyes in something, you are deeply involved or to have too much of something like work. ('Up the neck', 'up to the eyeballs' and 'up to the ears' are also used.)
Up to the neck
If someone's in something up to the neck, they are very involved in it, especially when it's something wrong.
Up to your eyes
When you've got too much work to do, you're up to your eyes in it.
Up to your neck
If someone is very involved in something, they are up to their neck in it, especially if it is something bad or immoral.
Up with the lark
If you get up very early, you're up with the lark.
Upper crust
The upper crust are the upper classes and the establishment.
Upper hand
If you have the upper hand, you have the advantage.
Upset the apple cart
If you upset the apple cart, you cause trouble and upset people.