Once in a blue moon is an expression meaning very infrequently or almost never.

Once in a blue moon simply means "rarely".

Hey vicki, how are you? ''Once in a blue moon'' is an informal expression that means ''very rarely''; ''almost never''. So far as that is concerend, if something happens ''once in a blue moon'', it happens once in a very long time (very seldom). Below you shall find a set of useful examples: E.g.: ''Once in a blue moon I have a little wine with dinner.'' E.g.: ''My friend only comes out for a drink once in blue moon now that he has kids.'' E.g.: ''Only once in a blue moon does she get to visit her daughter.'' E.g.: ''I wish I could travel abroad more often! Only once in a blue moon am I able to do so!'' *NOTICE: This term is something of a misnomer, believed to have stemmed from the fact that an actual blue moon, that is, the appearance of a second full moon in the same calendar month, occurs every 32 months or so. Further, the moon can appear blue in color at any time, depending on weather conditions. Hope that helps!!!

A blue moon happens when there's a fourth full moon in a single season. Usually, there are only three full moons in each season, so the blue moons rarely happen. Since it's such a rare event, we use the phrase "once in a blue moon" to describe something that doesn't happen very often. For example, here's some dialogue - Bob: "How often do you read the news?" Alice: "Every morning. And you?" Bob: "I only read it once in a blue moon." Hope this helped!

once in a blue moon (es raro) o casi nunca. but you can aslo say(once in a while) is almost the same (ex) do you drink? yea but, once in a blue moon or( once in a while)..