Residual is used to describe what remains of something when most of it has gone.
例句
...residual radiation from nuclear weapons testing...核武器實驗后殘留的輻射Turn the hotplate off and allow the residual heat to keep the mixture simmering.把烤盤關掉，讓余熱把混合物再煨一下。
英漢詞典釋義
adj.
存留下來的;剩余的;殘余的
a residual value of 10% of its original cost相當于原值10% 的余值
英英詞典釋義
Noun
1. something left after other parts have been taken away;
"there was no remainder""he threw away the rest""he took what he wanted and I got the balance"
2. (often plural) a payment that is made to a performer or writer or director of a television show or commercial that is paid for every repeat showing;