save, keep, etc. something for a rainy day成語所屬單字daysave, keep, etc. something for a rainy daysave, keep, etc. something for a rainy day — 慣用語慣用語1. To save something, especially money, for a future time of need.1.慣用語釋義未雨綢繆；以備不時之需To save something, especially money, for a future time of need.例句I put some money aside for a rainy day.She saved the extra cookies for a rainy day.