～色
～しょく · ～shoku · JLPT N2 · noun
color
🎨 原色 = origin + colour → primary colour; -shoku, like a shock of colour
In compounds, 色 is read shoku and names a kind of colour: 単色 (single + colour) is monochrome, and 原色 (origin + colour) is a primary colour. As a standalone word, 色 is read iro.
色 — person 人 (top) + kneeling figure 卩 (bottom)
Originally a pictograph showing one person above another, traditionally interpreted as depicting facial expressions or intimate posture between two people. The earliest meaning was 'facial expression' or 'countenance,' which extended to 'appearance' and eventually 'color' (the look of things). The 'shǎi' reading is a colloquial variant used for everyday color words.