单边
dān biān · HSK 7
unilateral
☝️ 单 dān (single) + 边 biān (side) = single-side, unilateral
One side acting alone. A unilateral decision is literally a single-side move — only one party calls the shot, no agreement needed from the other side.
单 — 叩 (two mouths 口) over 甲 (shield/armor)
Originally a pictograph of a forked hunting weapon or shield with two prongs at the top. The ancient form shows a Y-shaped tool, later stylized into the modern shape. The meaning shifted from the weapon to 'single' or 'one,' possibly because it was a single-handed tool.
边 — 辶 (walk) + 臱 (phonetic)
边 is the simplified form of 邊. It combines the walking radical 辶 with the phonetic component 臱, suggesting a place reached by walking — the edge or border of a territory. The meaning extended from 'frontier' to 'side' or 'edge' in general.