noun
year of a person's death
Used in biographical contexts, obituaries, and historical records to indicate the year someone died.
彼の没年は1989年です。
His year of death is 1989.
この作家の没年は不明だ。
The year of this author's death is unknown.
noun
one's age at death
Less common than the 'year of death' sense; often seen in formal or historical descriptions of a person's lifespan.
祖父の没年は82歳だった。
My grandfather's age at death was 82.
Compound of 没 (ぼつ, 'to die; to sink') and 年 (ねん, 'year'). The kanji 没 carries the meaning of 'passing away' in this context.