乙醛 yǐquán acetaldehyde Origin Definitions Defs Strokes Stroke Words Sentences Sents 乙 yǐ noun ethyl (bound form) Used in chemistry to refer to the ethyl group.醛 quán aldehyde (bound form) any of a class of organic compounds containing a carbonyl group with a single hydrogen atom; common examples include 甲醛 jiǎquán and 乙醛 yǐquán