1. the ten Heavenly Stems 甲[jia3], 乙[yi3], 丙[bing3], 丁[ding1], 戊[wu4], 己[ji3], 庚[geng1], 辛[xin1], 壬[ren2], 癸[gui3] (used cyclically in the calendar and as ordinal number like Roman I, II, III)