once in a blue moon

Cliché very seldom. Jill: Does your husband ever bring you flowers? Ellen: Once in a blue moon. Once in a blue moon, I buy a fashion magazine, just to see what people are wearing.

almost never Once in a blue moon I'll have a beer with friends, but it's not my regular drink.

very rarely My sister lives in Alaska, so I only get to see her once in a blue moon. I don't know why I bought that CD-ROM for my computer - I only ever use it once in a blue moon.

Rarely, once in a very long time, as in We only see our daughter once in a blue moon. This term is something of a misnomer, because 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. [Early 1800s]