薄
bó · HSK 4
light
🧊 薄 = 艹 (grass) + 溥 (spread thin) — thin grass, hence slight, cold, meagre
The 艹 radical marks plants; 溥 carries a 'spread wide and thin' sense. Combined, 薄 names anything stretched thin — thin fabric, thin soil (infertile), thin warmth (cold), thin kindness (unkind).
薄 — grass radical 艹 + 溥 (pǔ, phonetic)
薄 is a semantic-phonetic compound. The grass radical 艹 on top hints at the original meaning — thin, sparse vegetation or undergrowth. The lower part 溥 supplies the sound. From 'sparse plants' the meaning broadened to 'thin', 'slight', or 'meager' in general use.