expression, godan verb (-ru)
die; return to the earth
Euphemistic or poetic expression for dying, literally 'to become earth'. Used to soften the directness of death.
彼は戦場で土になった。
He returned to the earth on the battlefield.
いつかは誰もが土になる。
Everyone will eventually return to the earth.
Idiomatic phrase composed of 土 (earth) + に (particle) + なる (to become). The expression reflects a naturalistic view of death as returning to the earth.