noun, used as a suffix, noun
death anniversary; anniversary of a person's death
Commonly used as a suffix after a number, e.g. 一周忌 (first anniversary of death), 三周忌 (third anniversary). Also used as a standalone noun in formal contexts.
See also: 回忌
来月は祖父の三周忌です。
Next month is the third anniversary of my grandfather's death.
一周忌の法要を営みました。
We held a memorial service on the first anniversary of his death.