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Very rarely or infrequently, almost never
I only eat fast food once in a blue moon.
I rarely eat fast food.
She visits her hometown once in a blue moon.
She visits her hometown very infrequently.
The phrase emphasizes extreme rarity, often with a sense of surprise or exaggeration.
Use 'once in a blue moon' to describe events or actions that happen so rarely that they are almost unexpected.
Ensure the phrase is used in contexts where the rarity of the event is being emphasized, not just occasional occurrences.
The phrase originates from the rare occurrence of a 'blue moon,' which is an extra full moon that appears in a season or year. The term 'blue moon' itself has been used since the 16th century, and the phrase became popular in the 20th century to describe something that happens very infrequently.
This idiom is commonly used in informal contexts to emphasize how seldom something happens. It can be used for both positive and negative situations, depending on the context.