Definitions for "Yahrzeit"
(Yid.): the anniversary of a person's passing
Anniversary of a death. The immediate family of the person who died lights a candle that burns the entire day of the Yahrzeit. The candle honours the memory of that person.
(Yiddish) The anniversary of a death, usually marked by the lighting of a 24-hour (yahrzeit) candle and the recitation of Kaddish, the memorial prayer. In the US, the unveiling of the headstone usually takes place on or around the first yahrzeit.