Where does “心す” come from?

心す (Japanese) comes from Japanese 心, from Old Japanese 心, from Proto-Japonic *kəkərə — heart.

Ancestry of “心す”, step by step

心す traces back through two separate lines of ancestry.

via Japanese 心

StepLanguageWordMeaning
1Japanese心mind, heart, spirit, soul; thoughts, ideas;...
2Old Japanese心heart, mind, spirit; emotion, feeling; heart,...
3Proto-Japonic*kəkərəheart

via Japanese す

StepLanguageWordMeaning
1Japaneseすto do; 巣 nest, hive, den; 酢 vinegar
2Old Japaneseすto do; to happen, occur; to be in a state of...
3Proto-Japonic*sunest
Every word from Proto-Japonic *kəkərə →Every word from Old Japanese 心 →Every word from Japanese 心 →