Inseparable means impossible to pull apart or separate, or so closely connected that separating them would damage or destroy something important. When two best friends are inseparable, they spend nearly all their time together, finishing each other's sentences and choosing each other first for every activity.

The word describes both physical connections and emotional bonds. Peanut butter and jelly are inseparable in many people's minds: they just go together. In science, you might learn that certain chemical elements form inseparable compounds. A detective might discover that two events are inseparable, meaning one couldn't have happened without the other.

When people describe friends as inseparable, they're highlighting something special: a connection so strong that being apart feels wrong or uncomfortable. Think of Anne Shirley and Diana Barry in Anne of Green Gables, whose friendship was so deep they called themselves “kindred spirits.” That's what inseparable friendships look like.

The word can also apply to ideas: freedom and responsibility are often called inseparable because you can't really have one without the other. Sometimes people say certain rights and duties are inseparable, meaning they come as a package deal.