音読み: セイ・ショウ
訓読み: い
画数: 4
部首: に（二）
Meaning
Well / Community / Town Unit
- 井戸 — water well
- 井桁 — well frame (井-shaped structure)
- 天井 — ceiling
井 originally depicted a water well. Over time, it came to symbolize shared space and community, as well as the nine-square land division system in ancient China. It reflects both practical life and social organization.