Rosh hashanah has 3 different meanings across 2 categories:
(Judaism) a solemn Jewish feast day celebrated on the 1st or 1st and 2nd of Tishri; noted for the blowing of the shofar
A specific occurrence of this holiday.
The Jewish holiday marking the start of the liturgical year, taking place on the first two days of Tishrei, 163 days after the first day of Passover.