설날 • (seollal)
First attested in the Bullyu dugong busi eonhae (分類杜工部詩諺解 / 분류두공부시언해), 1481, as 섨날 (Yale: selsnal). Compound of 설 (seol, “new year, New Year's Day”) + 날 (nal, “day”), with genitive infix -ㅅ- (-s-).