粗い
あらい · arai · JLPT N2 · i-adj
rough
🌾🪨 arai sounds like a rye: a rye loaf is coarse and rough
粗 has 米 (rice) on the left, so it first meant unpolished, coarse grain. Coarse grain, like a rye loaf, feels rough. That gives the sense of 粗い: coarse, rough, not fine.
粗 — rice 米 + crude/rough 且
A semantic-phonetic compound. The left 米 (rice) hints at the meaning, since unhulled or coarsely milled rice is rough and grainy. The right 且 supplies the sound. From 'coarse rice' the meaning extended to 'thick, rough, crude' in general.