塞
sè · HSK 6
fill in
🧸 Earth (土) at the base — stuffing soil to plug a hole
The radical 土 (earth) sits at the bottom of 塞. Originally it meant blocking a frontier pass with packed earth. Today it simply means to stuff or fill any gap.
塞 — roof 宀 + 共 (hands) over 土 + 土
Originally depicted hands stuffing material between bricks under a roof to block gaps, giving the core sense 'to stop up' or 'block.' From this came extended meanings like 'frontier pass' or 'stronghold' (a blocked, fortified place), read sài. The reading sè keeps the verbal sense 'to fill in, plug.'