mutually; with each other; reciprocally
Polite adverbial form of 互いに, used when two or more parties do something to or for each other. Often implies a cooperative or reciprocal action.
See also: 互いに
Let's help each other.
We decided to keep in touch with each other.
Let's help each other out when we're in trouble.
Let's both be careful not to catch a cold.
It's important to talk things through and understand each other.