The conversation between human and AI assistant.
What is the meaning and origin of the idiom "once in a blue moon"?
Can you tell me the meaning and origin of the idiom "once in a blue moon"?
Sure, "once in a blue moon" is an expression used to describe an event that occurs rarely or seldomly. The origin of this phrase is traced back to the 16th century when the phrase "blue moon" was used to denote the third moon in a season that had four full moons rather than three. Thus, the blue moon was considered a rare occurrence and the phrase eventually evolved into the figurative expression we use today.