Jul 15

Idioms with 'blue'

Idiomatic expressions can be used in IELTS Speaking and in IELTS General Writing Task 1 if it is an informal letter.

Look at the following sentences containing idioms. Can you work out the missing word. It is the same in both sentences:

a) When I was younger, I used to play the trumpet practically every day. Now I just don’t have time. I only take it out of its case once in a ______ moon.
A clock and the question 'How often?'
b) Completely out of the ______ I got a phone call from an old college friend. She wanted to know if I would like to meet her for a coffee. It shocked me as we haven’t actually seen each other for about twenty years.
A person showing surprise
ANSWER: blue

Once in a blue moon = very infrequently; occasionally; very unusually
Out of the blue = completely unexpectedly; with no indication that it would happen 


  • I only go to the local Lebanese restaurant once in a blue moon. Although the food is absolutely scrumptious, it costs an arm and a leg to go there.

  • My boss called me into her office, completely out of the blue, and offered me a promotion and a pay rise. It was a huge shock and I didn’t know what to say. I just nodded.


To be scrumptious = to be extremely tasty
To cost an arm and a leg = to be extremely expensive
To nod = to move your head up and down to indicate that you agree with something or somebody
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