What does blue moon mean?

blue moon meaning in General Dictionary

the 2nd full moon happening in identical month based on the appearance once in a blue moon once we had a blue moon on January 31 1999 and another in March

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  • quite a long time

blue moon meaning in Etymology Dictionary

1821 as a particular term in sense "very hardly ever," maybe suggesting something which, in reality, never ever occurs (compare at the Greek calends, additionally the local in reign of Queen Dick and Saint Geoffrey's Day "Never, there becoming no saint of this name," reported in Grose (1788)); advised earliest within couplet from 1528:Yf they say the mone is blewe,we ought to beleve that it is true. Though this might relate to calendrical calculations by the Church. Therefore the typical "rareness" sense of the definition of is difficult to disentangle through the certain calendrical one (commonly misinterpreted as "second full moon in a calendar thirty days," but actually a quarterly calculation). Either way, the sense of azure here is obscure. Literal blue moons do occasionally occur under extreme atmospheric conditions.