Idioms based on colour and colours. Select an idiom for more details. Also try Colour Idioms Quiz.
A red-letter day is a day that is very important for some reason.
If you tell a white lie, you say something that isn't true in order to be polite or so as not to hurt someone's feelings.
If someone is caught red-handed, they are caught in the act of doing something wrong such as cheating or stealing.
If you give something the green light, you give permission for it to be done, or allow it to happen.
If a person or a company is in the black, their assets are greater than their debts.
If you're in the dark about something, you don't know about it.
If a person or a company is in the red, their debts are greater than their assets.
If you kill the goose that lays the golden egg, you destroy something that has made you a lot of money.
If something happens once in a blue moon, it happens very rarely.
If something happens out of the blue, you're not expecting it to happen and you're surprised when it does.
If you paint the town red, you visit bars, nightclubs and other nightspots to have a good time.
A red light district is the area of a town or city in which prostitutes work.
Strict adherence to rules and regulations so that a procedure seems to take longer than necessary.
If you see red, you become extremely angry.
If someone sees things through rose-coloured glasses, they see things as being better than they really are.
You show your true colours if you show what you're really like, or you reveal your true character.
If you pass a test with flying colours, you pass it easily and get high marks.
Journalism in which sensational stories are used to boost sales, or biased reporting is used to change the reader's views on an issue. Both of these are unethical.
If someone has a yellow streak, they can sometimes act in a cowardly way and not be very brave.
If someone is yellow-bellied, they are not brave, or they are cowardly.