Inactive means not active, not working, or not doing anything. When a volcano is inactive, it hasn't erupted in a long time and shows no signs of erupting soon. When an account is inactive, no one has used it recently. When your leg muscles become inactive during a long car ride, they're not moving or working.

The word often suggests something that could be active but currently isn't. An inactive club member hasn't quit, they're just not participating right now. An inactive ingredient in medicine is present in the pill but doesn't actually treat your illness. It's different from something that's permanently broken or dead: an inactive phone can be reactivated, but a broken phone needs repair.

Scientists use inactive precisely. An inactive gene is still in your DNA but isn't currently making proteins. An inactive chemical won't react with other substances. In everyday language, someone might call themselves physically inactive if they spend most of their time sitting rather than moving around. The opposite of inactive is active, meaning engaged, working, or in motion.