十天干 shí tiān gān the ten Heavenly Stems 甲 jiǎ, 乙 yǐ, 丙 bǐng, 丁 dīng, 戊 wù, 己 jǐ, 庚 gēng, 辛 xīn, 壬 rén, 癸 guǐ (used cyclically in the calendar and as ordinal number like Roman I, II, III)