O
(as of Dec 7, 2007)- Off the Top of Your Head
- On a Shoestring
- On Cloud Nine
- On Pins and Needles
- On Top of the World
- Once in a Blue Moon
- Open a Can of Worms
- Over the Hill
Sample Idiom
Once in a Blue Moon
Sentence
I go to the library once in a blue moon.
Explanation
very seldom; hardly ever
Origin
This expression was first used in the early 1500s. Some people noticed on some nights
when the bright part of the moon is a crescent, they say the other part of the moon
has a bluish color to it. This "blue moon" phenomenon rarely happens. Thus, the birth
of this expression, and has been popular ever since.
