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life; life force
lifetime; lifespan
most important thing; foundation; core
「命」 has other readings with different meanings.
命を大切にすることを忘れないで。
Don't forget to value life.
この機械の命はあと数年だろう。
This machine's lifespan is probably only a few more years.
信頼が会社の命だ。
Trust is the lifeblood of a company.