Yom Kippur[yäm′ki po̵or′, yôm′-, -kip′ər]
Yom Kippur definition by Webster's New World
Origin: Classical Hebrew (language) yom-kipur ; from yom, day plush kipur ; from kiper, atone ; from root kpr, deny, disavow
Yom Kippur definition by American Heritage Dictionary
Origin: Hebrew yôm kippûr : yôm, day; see ywm in Semitic roots + kippûr, atonement (from kippēr, to cover, atone; see kpr1 in Semitic roots).
Yom Kippur - Cultural Definition
In Judaism, the Day of Atonement, the most important religious holiday; a day of fasting to atone for sins. It comes in autumn. (See Rosh Hashanah.)