first of the ten Heavenly Stems 十天干[shi2 tian1 gan1], (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[bao3 jia3] system (old), ancient Chinese compass point: 75°