blue · adjective /bluː/Full view
blue (COLOUR)
A1 being the same colour as the sky when there are no clouds
Dictionary examples:

a dark/light/pale blue jacket

She has big blue eyes.

Learner example:

I like her long brown hair and blue eyes. (Skills for Life (Entry 1); A1; Albanian)

blue (SAD)
C2 sad
Dictionary example:

I was feeling blue.

Learner example:

Do you feel the need to dress, behave and consume the same products as your friends? Are you the kind of person who go[es] shopping when you feel blue or a little morose? (Certificate of Proficiency in English; C2; Portuguese)

blue · noun C or U /bluː/
blue
A2 a blue colour
Dictionary example:

There's a lot of blue in this room.

Learner example:

I want my bedroom to be painted in yellow and blue. (Key English Test; A2; Hindi)

out of the blue
C1 If something happens out of the blue, it is completely unexpected.
Dictionary example:

One day, out of the blue, she announced that she was leaving.

Learner example:

Dear Kim, I was extremely happy when I received your letter out of the blue. (Certificate in Advanced English; C1; Greek)

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