Rosh Hashanah UK /ˌɹɒʃ həˈʃɑːnə/US /ˌɹɑʃ(h)əˈʃɑnə/ noun2 •A specific occurrence of this holiday. •(Judaism) 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.The past two days we have celebrated Rosh Hashanah, the Jewish New Year. — 2021 formsRosh Hashanahs