life; breath of life
Idiomatic expression used almost exclusively in the phrase 息の根を止める, meaning to kill or to put an end to someone's life. Not used as a general word for 'life'.
The criminal put an end to the victim's life.
Compound of 息 (breath) + の (possessive particle) + 根 (root). Literally 'the root of breath', referring to the source of life. The exact historical derivation is uncertain, but the expression is conventionally associated with the idea of stopping someone's breath.