Practice
Colour idioms: understand common figurative English
Sign in to saveA colleague says that a rule came out of the blue. The rule is not blue. It appeared unexpectedly. Colour idioms use familiar colour words, but their meaning comes from the full phrase and the situation.
Understand six common colour idioms from context, explain their figurative meanings, and choose plain English when an idiom may confuse the listener.
Read and practice
Read the examples and try the written questions in this guide. Listening recordings are not available for this lesson yet.
Try the written questions
once in a blue moon /wʌns ɪn ə bluː muːn/
The short answer
Learn a colour idiom as one complete phrase. Out of the blue means unexpectedly, green with envy means very jealous, red tape means slow or excessive official procedures, and once in a blue moon means very rarely.
Out of the blue, Nadiya received an invitation to speak at a local event.
Why it works: The invitation was a surprise. The phrase describes the unexpected event, not the colour of the invitation.
5 more examples
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Tomas was green with envy when his sister showed him her new studio.
Tomas felt strong jealousy about something his sister had.
Not this:Tomas
was pleasedthat his sister found a new studio. What changes: This describes happiness for another person, not jealousy. -
The café owner spent two weeks dealing with red tape before the outdoor tables could open.
The owner saw the official process as slow or unnecessarily complicated.
Not this:The café owner completed the
required fire safety checkbefore opening the outdoor tables. What changes: This names a specific necessary step without criticizing it as excessive. -
The rental agreement puts the repair dates in black and white.
The dates are clearly written in the agreement.
Not this:The repair dates were
mentioned during a phone call. What changes: A phone call may not provide the same written record. -
Once in a blue moon, I buy a paper map for a long trip.
The speaker buys a paper map very rarely.
Not this:I buy a paper map
before every long trip. What changes: This is a regular habit, so once in a blue moon would be inaccurate. -
When the contractor ignored the agreed safety plan, Priya saw red.
Priya became suddenly very angry.
Not this:Priya
calmly askedthe contractor to explain the change. What changes: This reaction is controlled and does not describe sudden anger.
Read the full guide
Start with the event or feeling in the sentence. Then replace the idiom with a plain phrase and check whether the whole message still makes sense. For example, if a company loses time to red tape, it is dealing with procedures that seem slow or unnecessary. The sentence does not describe red pieces of tape.
Read the situation before you translate the words
Do not decide an idiom's meaning from one colour word. In a sentence about a surprise, out of the blue means unexpectedly. In a sentence about paint, blue may describe a real colour. The speaker, event, and result tell you which reading fits.
Out of the blue, Nadiya received an invitation to speak at a local event.
The event was a surprise. A planned invitation after an application is different.
A friend calls after ten years without contact. What does out of the blue tell you?
The call was unexpected. The phrase does not describe the colour of a phone or message.
Use out of the blue for an unexpected event
Use out of the blue for an event, message, decision, or appearance that was not expected. It can describe welcome news, worrying news, or a neutral surprise. The phrase is common in conversation and informal writing. Do not use it for something already arranged or scheduled.
Out of the blue, a former classmate sent Luis a useful job link.
A former classmate sent Luis the link after their planned call describes an expected follow-up.
Does out of the blue fit a newsletter that arrives every Friday?
No. A regular newsletter is expected. Say that it arrives every Friday instead.
Describe jealousy without mistaking it for a colour
Green with envy means very jealous. It usually refers to a person who wants something another person has or resents another person's good fortune. Friends may use the phrase playfully, but it can sound accusing during a real disagreement. Name the feeling directly when that is kinder or clearer.
Tomas was green with envy when his sister showed him her new studio.
Tomas was happy for his sister has a different meaning. It shows support rather than jealousy.
Which feeling does green with envy describe: jealousy or relief?
It describes jealousy. The context often tells you what the person wants or resents.
Use red tape only when you mean criticism
Red tape refers to official forms, rules, or approvals that a speaker sees as excessive, slow, or needlessly complicated. It usually expresses frustration. A safety inspection or legal requirement is not automatically red tape. In a formal message, identify the form, approval, or deadline that caused the delay.
The café owner spent two weeks dealing with red tape before the outdoor tables could open.
The café owner completed the required fire safety check identifies a process without judging it.
What is clearer in a complaint than saying there was red tape?
Name the required document or approval, say when it was requested, and explain the delay.
Ask for a written record in black and white
If information is in black and white, it is written down clearly. The expression often concerns an agreement, instruction, rule, or date that people may need to check later. Written words can still need interpretation, but the phrase tells you that a record exists.
The rental agreement puts the repair dates in black and white.
A phone call may communicate the dates, but it does not create the same written evidence.
Why might a manager ask for a decision in black and white?
The manager wants a written record that people can read and refer to later.
Use once in a blue moon for something rare
Once in a blue moon means very rarely. It is informal and gives no exact frequency. It can describe an occasional habit, such as eating at a certain restaurant or taking a particular route home. Use dates or numbers when the exact schedule matters.
Once in a blue moon, I buy a paper map for a long trip.
I buy a paper map before every long trip describes a regular habit, not a rare event.
Would once in a blue moon suit something you do every day?
No. Use it for an event that happens very rarely.
Recognize sudden anger in see red
See red means become suddenly very angry. It can describe a strong reaction to unfairness, danger, or an insult. The phrase may sound dramatic, especially in writing about a serious conflict. A direct sentence such as Priya became angry is calmer when the level of emotion is uncertain.
When the contractor ignored the agreed safety plan, Priya saw red.
Priya calmly asked for an explanation describes a controlled response rather than sudden anger.
When might a direct sentence be better than see red?
Use a direct sentence in a formal report or when you need to describe the reaction without drama.
Before you go
Remember this
Read colour idioms as complete expressions and use context to check the meaning. Out of the blue describes a surprise, green with envy describes jealousy, red tape describes frustrating procedures, in black and white describes a written record, once in a blue moon describes a rare event, and see red describes sudden anger.
Practice with the written examples
You can practice with the written questions in the Learn tab. Each answer includes an explanation.
Try the written questionsListening test not available yet
This lesson does not have the recordings needed for a listening test. Use the written questions in the guide to check your understanding.
Try the written questionsQuestions about "Colour idioms: understand common figurative English"
What does out of the blue mean?
Out of the blue means unexpectedly. Use it for a message, event, or decision that was not planned or expected. It suits the invitation example because Nadiya did not expect the event organizer to contact her.
Out of the blue, Nadiya received an invitation to speak at a local event.
What does green with envy mean?
Green with envy means very jealous of another person's possession, opportunity, or good fortune. Tomas feels this way when he sees his sister's new studio. In a serious disagreement, a plain description of jealousy may sound less accusing.
Nadiya received an invitation after she applied to speak at the event.
What is red tape in English?
Red tape means official procedures or paperwork that a speaker considers excessive, slow, or unnecessarily difficult. It often carries criticism. In a formal complaint, name the approval, form, and delay so the reader can understand the specific problem.
Tomas was green with envy when his sister showed him her new studio.
What does in black and white mean?
In black and white means clearly written down. The rental agreement gives the repair dates in a written record that people can check later. The phrase refers to documented information, not to a particular ink color.
Tomas was pleased that his sister found a new studio.
How often is once in a blue moon?
Once in a blue moon means very rarely. It is an informal expression, so it does not give an exact schedule. Use a date, number, or regular frequency when the listener needs precise timing.
The café owner spent two weeks dealing with red tape before the outdoor tables could open.