十天干 shítiāngān

shítiāngān noun the ten Heavenly Stems
Domain: Modern Chinese 现代汉语
Notes: 甲, 乙, 丙, 丁, 戊, 己, 庚, 辛, 壬, 癸, used cyclically in the calendar and as ordinal number like Roman I, II, III (CC-CEDICT '十天干')