Kanji for Life — 命

命 is read inochi on its own and mei or myō in compounds. It means life — but specifically the life you are given and can lose, the thread that runs from birth to death. 命がけ (inochigake) means staking your life on something.

The same character also means command or decree: 命令 (meirei) is an order, 命じる (meijiru) to command. Both senses come from the same root idea of something handed down from above, which is why 運命 (unmei) means fate and 使命 (shimei) a calling or mission.

命 and 生 divide the concept between them. 生 (sei) is life as living and growing — 生活 (seikatsu) daily life, 生きる (ikiru) to live, 人生 (jinsei) a human life as a course of experience. 命 is the life force itself. For “save a life” you need 命 (命を救う); for “way of life”, 生.