Mutually means that something applies to two or more people or groups in the same way, with each side experiencing or doing the same thing. When two friends have mutually agreed on a movie to watch, they've both said yes to the choice. When countries sign a mutual agreement, both sides make a promise to each other.

The word emphasizes reciprocity: what's true for one side is true for the other. If you and your sister are mutually responsible for cleaning your shared room, you both share the responsibility. If two classmates have a mutual respect for each other, each one respects the other in return.

You'll often hear the phrase mutually beneficial, which describes a situation where everyone involved gains something. When your neighbor watches your cat while you're away and you water their plants while they're gone, that's mutually beneficial: both families get help.

The opposite would be one-sided, where only one person feels or does something. Mutual feelings, interests, or agreements involve everyone, not just one person.