out of the blue

Register · Informal Informal — used in casual, everyday conversation among friends and family. Avoid in formal writing or professional settings. CEFR B2

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Figurative meaning

suddenly and unexpectedly

Why this phrase?

'The blue' means the clear sky; something unexpected appears from nowhere.

Example

“She called me out of the blue after ten years.”

Dictionary details

Tags

Expressions connected by reviewed component words or topic tags.

on cloud nine Informal · CEFR B1

Extremely happy and delighted.

hang on a minute Informal · CEFR A2

used to ask someone to wait, or to express surprise or objection

how on earth Informal · CEFR B1

an emphatic way of asking 'how', expressing surprise or disbelief

rain cats and dogs Informal · CEFR B1

to rain very heavily

ring a bell Informal · CEFR B1

to sound familiar or remind you of something

under the weather Informal · CEFR B1

Feeling slightly ill or unwell.

Source methodology

Meanings, register, CEFR, and examples come from the reviewed dictionary record. Expression notes may describe a reviewed present-day word picture or a background note; they are not presented as verified etymology.

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