平面
píngmiàn · HSK 7
plane
📄 平 = flat/level + 面 = face/surface; a flat surface is a plane
平 carries the sense of flat or level (as in 平 = level ground), and 面 means face or surface. Put together, 平面 names a flat face: a plane or planar surface in geometry.
平 — horizontal stroke 一 + 干 with two dots 八
平 originally depicted a balance or scale being level, suggesting evenness. The horizontal lines and symmetrical dots evoke a flat, balanced surface. Over time it extended from 'level/flat' to broader senses like 'calm,' 'peaceful,' and 'ordinary.'
面 — enclosure 囗 + 自 (nose/face inside)
Originally a pictograph showing a face framed by an outline, with 自 (nose) inside representing the central feature of the face. The early meaning was 'face,' which extended to 'surface,' 'side,' and 'aspect.' In simplified Chinese, 面 also absorbed 麵, adding the meaning 'flour/noodles.'