aldehyde

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

butyraldehyde; butanal

furfural (chemistry)

phenolic aldehyde; phenolic resin (used to manufacture bakelite)

formaldehyde (HCHO)

(chemistry) aldehyde