Fetching details from the dictionary...
3rd day of the month
three days
三みっ日かから旅行りょこうに行くいく。
I'm going on a trip starting the third.
三みっ日かかん間休みやすみましたよ。
I took three days off.
三みっ日かかん間ずっと雨あめが降りふり続けつづけた。
It rained continuously for three days.