The idiom out of the blue means something that happens unexpectedly or without warning. It is often used to describe events that are surprising or shocking, either in a positive or negative way. For example:
- Out of the blue, he proposed to her on their anniversary.
- She got a call out of the blue from her long-lost cousin.
- The storm came out of the blue and ruined our picnic.
The origin of this idiom is not very clear, but some sources suggest that it is derived from an older expression a bolt out of the blue or a bolt from the blue, which refers to a sudden flash of lightning from a clear sky. This image of something unexpected coming from the sky may have inspired the shorter version of the idiom.
Some synonyms for out of the blue are:
- out of nowhere
- without warning
- all of a sudden
- like a bolt from the blue
