blue moon

/ˈblu ˈmun/
/blu mun/
IPA guide

Other forms: blue moons

Definitions of blue moon
  1. noun
    the second full moon in a month
  2. noun
    the third full moon in a season that has four
  3. noun
    a rare event when the moon appears blue due to the presence of smoke or dust particles in the atmosphere
  4. noun
    a long time
    “something that happens once in a blue moon almost never happens”
    see moresee less
    type of:
    age, long time, years
    a prolonged period of time
  5. noun
    a rare or infrequent event
Cite this entry
Style:
MLA
  • MLA
  • APA
  • Chicago

DISCLAIMER: These example sentences appear in various news sources and books to reflect the usage of the word ‘blue moon'. Views expressed in the examples do not represent the opinion of Vocabulary.com or its editors. Send us feedback
Word Family

Vocabulary lists containing blue moon

view more about the vocabulary list
Ides, Eon, Epoch, and Era: Time-related Words

Beware the ides of March, and other obscure time-related words that you only see once in a blue moon. Learn these terms in a fortnight (perhaps less?), and usher in a new era of vocabulary knowledge. Read the full article: Beware the Time-related Vocabulary of March!

MORE VOCABULARY LISTS