reciprocal

A reciprocal situation is when people do the same thing for each other, or give and receive something equally.

When we talk about reciprocity, it's often about relationships between two people. For example, if your friend lends you money, and then you lend them money later, that's a kind of reciprocal relationship. You're both doing the same thing for each other, helping each other out in return. This can also happen with favors - if someone does something nice for you, like watching your cat while you're away, you might do the same for them next time they need help.

In other cases, the word "reciprocal" is used to describe things that are exact opposites, or have a special connection. For instance, in mathematics, a reciprocal number is one that's exactly flipped around - like 1/2 being the reciprocal of 2 (or vice versa). In science, some relationships between two things can be considered reciprocal too - for example, a force and its reaction to that force are often seen as reciprocal actions.