双边
shuāng biān · HSK 7
bilateral
↔️ 双边 = 双 (double/pair) + 边 (side) = two-sided = bilateral
双 means a pair or double; 边 means side or edge. Put them together and you get two-sided, which is exactly what bilateral means: between two parties or sides.
双 — two 又 (right hands) side by side
Originally written 雙 with two 隹 (short-tailed birds) over 又 (hand), depicting a pair of birds held in one hand, hence 'pair' or 'two'. The modern simplified form 双 keeps just two 又 hands side by side as a visual shorthand for 'a pair'. Meaning broadened to 'double' or 'even-numbered'.
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.