blue moon

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blue moon

A blue moon is a rare and special event.

Definition
  1. Noun:
    • A very long period of time; an indefinite, extended duration. This meaning is primarily used in the idiomatic phrase "once in a blue moon."
    • A rare or unusual event. Refers to something that occurs very infrequently.
Usage

The term "blue moon" is almost exclusively used in the fixed idiomatic expression "once in a blue moon." This phrase functions as an adverbial phrase to describe the extreme rarity of an event.

Examples
  • Noun (in idiom):
    • My sister lives abroad, so I only see her once in a blue moon.
    • He's very careful with his money and eats at a restaurant only once in a blue moon.
    • Such a total eclipse of the sun happens only once in a blue moon.
Advanced Usage
  • "a blue moon": Can be used poetically or figuratively to mean a very rare occurrence, though this is less common than the full idiom.
    • Opportunities like this come along only a blue moon.
Variants and Related Words
  • Blue moon: In modern astronomy, a "blue moon" can refer to the second full moon in a single calendar month, which is the origin of the idiom's meaning of rarity. This is a separate, technical definition.
  • Rarity (n): The state or quality of being rare.
  • Infrequency (n): The state of not happening often.
Synonyms
  • Rarely
  • Seldom
  • Hardly ever
  • Infrequently
Related Idioms
  • Once in a blue moon: Very rarely; almost never.
    • He visits his hometown once in a blue moon.
  • Every blue moon: An occasional variant with the same meaning as "once in a blue moon."
    • We get a chance to relax like this every blue moon.
blue moon

A blue moon is a rare and special event.

Noun
  1. a long time
    • something that happens once in blue moon almost never happens