断面
だんめん · danmen · JLPT N1 · noun
cross section
断 — thread 㡭 (silk bundle) + axe 斤
Originally written with 㡭 (entangled silk threads) on the left and 斤 (axe) on the right, depicting an axe cutting through bundled threads. From this concrete image of severing came the meanings 'to cut off,' 'to break,' and by extension 'to decide' or 'judge'—as in resolving a matter decisively.
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.'