noun, noun or participle which takes 'suru'
Literary or archaic term for taking one's own life, often with a nuance of dying to atone for a fault or to preserve honor. Not used in everyday modern speech.
武士は恥をかくくらいなら生害を選ぶこともあった。
A samurai would sometimes choose to commit suicide rather than face disgrace.
自殺 is the standard modern word for suicide. 生害 is an archaic, literary term with a nuance of honorable atonement.
The exact derivation is uncertain. The kanji 生 (life) and 害 (harm) together suggest 'harming one's own life', i.e., suicide.