生理
せいり · seiri · JLPT N3 · noun
physiology
🩸 生理 = life + principle: the workings of the body
生 means life or birth, and 理 means principle or logic, as in 理科 (science). So 生理 is the science of how the body works. In everyday Japanese it is also the polite word for a period, as in 生理痛 (seiritsuu, period pain).
生 — sprout 屮 above earth 土
Originally a pictograph showing a young plant sprouting from the ground, with 屮 (a sprout) above 土 (earth). The core meaning is 'to be born, to grow, to live,' which extends to 'raw, unripe, unfamiliar.' The modern form has simplified the sprout shape but preserves the image of new growth emerging from soil.
理 — jade radical 玉/王 + village 里 (phonetic)
理 is a semantic-phonetic compound: the jade radical 王 (玉) on the left signals meaning, while 里 on the right gives the sound. It originally meant the natural veins or grain in a piece of jade, then extended to 'pattern,' 'order,' 'principle,' and finally the modern senses 'reason' and 'to manage.'