first of the ten Heavenly Stems 十天干; (used for an unspecified person or thing); first (in a list, as a party to a contract etc.); letter "A" or roman "I" in list "A, B, C", or "I, II, III" etc.; armor plating; shell or carapace; (of the fingers or toes) nail; bladed leather or metal armor (old); ranking system used in the Imperial examinations (old); civil administration unit in the baojia 保甲 system (old); ancient Chinese compass point: 75°

fingernail

deck (of a boat etc.)

carapace; crust; outer shell; also pronounced jiǎ ké

vehicle armor

first year of the sixty-year cycle (where each year is numbered with one of the 10 heavenly stems 天干 and one of the 12 earthly branches 地支); the sixty-year cycle

beetle

methane CH4