息
ソク, いき

breath, respiration, son, interest (on money)

JLPT3 G3 S10 F882

As per 自# (nose) + 心 heart/emotions → breathe through the nostrils in rhythm with the beating of the heart → *breath* → *live* → *give birth*; *increase*. Also, *stop*; *rest* (← stops and starts of steady breathing); *interest* (← increase); *son* (← give birth).

[Full Kanji Etymology List]