by-product
noun [ C ] uk/ˈbaɪˌprɒd.ʌkt/ us/ˈbaɪˌprɑː.dəkt/
副产品；附带产生的后果
something that is produced as a result of making something else, or something unexpected that happens as a result of something
Buttermilk is a by-product of making butter. 脱脂牛奶是制造黄油时的副产品。
Illness is one of the by-products of overcrowded housing. 居住条件过度拥挤的后果之一是滋生疾病。