From Old Chinese 左 (OC *ʔsaːlʔ, *ʔsaːls). Cognate with Thai ซ้าย (sáai), Lao ຊ້າຍ (sāi), Shan သၢႆႉ (sâ̰ai), Ahom 𑜏𑜩 (say), Zhuang swix.
soix