afterthought
noun [ C usually singular ] uk/ˈɑːf.tə.θɔːt/ us/ˈæf.tɚ.θɑːt/
事后想法;事后添加的事物
an idea, thought, or plan that was not originally intended but is thought of at a later time
She only asked me to her party as an afterthought. 她原本没有请我去参加她的聚会，只是后来才想起来的。
The pillars seem to have been added to the entrance as an afterthought. 这些柱子好像是完工后在入口处添加上去的。