fiftieth day after a child's birth
Traditional Japanese milestone; families often celebrate the baby's health and growth on this day.
We celebrated the baby's fiftieth-day milestone.
fifty days
Literal count of fifty days; less common than the milestone sense.
Please pay within fifty days of the contract.
mochi for a child's 50th day celebration
Compound of 五十 (fifty) and 日 (day), with the irregular reading いか likely from older Japanese counting.