The phrase "once in a blue moon" is an idiom meaning something that happens very rarely or infrequently. It expresses the idea of an event occurring only on rare occasions, not regularly or often
. Origin and Meaning:
- Historically, a "blue moon" referred to the rare occurrence of a fourth full moon in a season, which usually has only three full moons. More recently, it has come to mean the second full moon in a single calendar month, which happens roughly every two to three years
- The idiom uses this astronomical rarity figuratively to describe events that happen seldom or almost never
- The phrase dates back at least to the early 1500s in English, originally used in contexts implying something unusual or rare
Examples of Usage:
- "Once in a blue moon I go to a concert, but only when there is a singer I really like."
- "Because I live abroad, I get to see my parents once in a blue moon."
- "I'm very careful about what I eat, so it's only once in a blue moon I eat fast food."
In summary, "once in a blue moon" means an event or action that happens very rarely, drawing from the infrequent astronomical event of a blue moon
