The matter of life and death; The care for human life; The rabbinic concept that states that the effort to save a human life supersedes and takes precedence over all the mitzvot of the Torah, with the exception of idolatry, murder, and forbidden sexual relations
(peek-koo-akh NE-fesh) n. A fundamental rabbinic principle of the saving of a human (Jewish) life. For the sake of Pikuach Nefesh, any holiday prohibition may be broken.
In Judaism, pikuach nefesh is the obligation to save a life in jeopardy. Pikuach nefesh supersecedes virtually all Jewish law, including Shabbat. For example, a Jewish doctor may work on Shabbat in the case that patients may die if he would not.