From Proto-Tai *selꟲ (classifier for long, thin objects). Cognate with Thai เส้น (sên), Lao ເສັ້ນ (sen), Shan သဵၼ်ႈ (sāen), Saek แซ̂น. Compare Middle Chinese 線 (MC sjenH, “thread”).
ᥔᥥᥢᥲ (sèn) (1963 orthography ᥔᥥᥢ̀)