[mass noun]voluntary sexual intercourse between a married person and a person who is not their spouse 私通,通奸 she was committing adultery with a much younger man. 她和一个比她年轻得多的男人私通。
语源
late 15th cent.: from the obsolete noun adulter, from Latin adulter 'adulterer', replacing an earlier form avoutrie, from Old French avouterie