圆形
yuán xíng · HSK 7
circular
⭕ 圆 round + 形 shape/form = a round shape
圆 carries the round/circle sense, while 形 means shape or form (same 形 as in 形状). Stack them and you get round-shape: a circular form. The yuán of 圆 also means a unit of currency, but here it stays literally round.
圆 — enclosure 囗 + 員 (phonetic)
圆 is a phono-semantic compound. The outer 囗 (enclosure) suggests a round, closed shape, while 員 provides the sound and originally depicted a round-mouthed tripod vessel. Together they came to mean 'round' or 'circle,' later extending to 'complete' and the unit of currency.
形 — open frame 开 + hair/pattern 彡
形 combines 开 (originally a phonetic element suggesting the sound) with 彡, a radical depicting fine lines, hair, or decorative strokes. The 彡 part conveys the idea of visible markings or surface appearance, giving 形 its core meaning of 'shape' or 'form.' Over time it broadened to cover physical figure, appearance, and abstract form.