Reactivation usually refers to making something active or useful again after it was dormant or inactive.
When you hear about reactivation, think of things that used to work but stopped working for some reason. Maybe a company had to close down its factory due to financial problems, but now they're putting in new money and reopening the plant - this is an example of reactivation. In medicine, doctors might talk about reactivating a treatment plan to help someone recover from a sickness that was dormant or went into remission. Sometimes, governments will reactivate old laws or regulations when there's a need for them again.
The activation of something previously inactive or inactivated.
