once in a blue moon

Etymology
See.

Adverb

 * 1)  Very rarely; very infrequently.

Translations

 * Chinese:
 * Cantonese: 千載難逢, 十年唔逢一閏
 * Mandarin:
 * Czech:
 * Dutch: eens in de zoveel tijd
 * Esperanto: ege malofte
 * Finnish: todella harvoin
 * French:, une fois toutes les lunes
 * Georgian: ათასში ერთხელ
 * German:
 * Greek:
 * Irish: uair sna naoi n-aird, uair umá seach
 * Italian: una volta ogni morte di papa, ogni morte di papa
 * Japanese: ごくまれ
 * Polish: ,
 * Portuguese:, uma vez na vida, outra na morte
 * Russian: раз в сто ле́т
 * Scottish Gaelic: uair san ràith
 * Slovak: raz za uhorský rok
 * Spanish:, de guindas a brevas, de higos a brevas, , ,
 * Thai: มากไม่ค่อย
 * Turkish: kırk yılda bir