Yom Kippur
Concise Oxford English Dictionary © 2008 Oxford University Press:
Yom Kippur /jɒm kɪˈpʊə, ˈkɪpə/
▶noun the most solemn religious fast of the Jewish year, the last of the ten days of penitence that begin with Rosh Hashana (the Jewish New Year).
– origin Heb. Yōm Kippūr, from yōm ‘day’ + kippūr ‘atonement’.
'Yom Kippur' also found in these Oxford entries:

