拡散
かくさん · kakusan · JLPT N1 · noun
diffusion
散 — 月 (meat) + 攵 (action) + 卄 (hemp fibers)
Originally depicted beating hemp fibers apart with a stick, with 月 (meat/flesh) added later. The core image of separating or scattering things gave rise to meanings like 'scatter,' 'disperse,' and 'loose/leisurely.' The 攵 component signals an action done by hand.