For others, it was an experience of drudgery. Making three meals a day, especially if your diners included small children, was tedium defined—an endless loop of eggs and beans and eggs and toast and beans and toast and eggs.
参考译文：对于另一些人而言，这段经历则是单调乏味的。每天准备三餐，特别是如果家中有小孩的话，这无疑是一份枯燥乏味的苦差事——鸡蛋、豆子、吐司换着花样搭配。

备注(1)：defined 为过去分词作后置定语修饰前面抽象名词, tedium defined=tedium which was defined.

Making three meals a day, especially if your diners included small children, was tedium defined—an endless loop of eggs and beans and eggs and toast and beans and toast and eggs.
=Making three meals a day was tedium defined—an endless loop of eggs and beans and eggs and toast and beans and toast and eggs,especially if your diners included small children,

备注(2): especially if your diners included small children, 为句子状语，放在中间，把句子主语和表语分隔开来。

Making three meals a day【主语】// was 【系动词】//tedium 【表语】defined【后置定语】//