to share the same feelings as someone else, or to behave in the same way as someone else

Sadly, my feelings for him were not reciprocated. 很不幸，我为他付出的感情没有得到回报。

We invited them to dinner and a week later they reciprocated. 我们请他们吃晚餐，一星期后他们回请了我们。

If a part of a machine reciprocates, it moves backwards and forwards.

Some electric razors have reciprocating heads. 有些电动剃须刀的刀头是往返运动式的。