Other forms: reactivated; reactivating; reactivates
Whether it’s a slumping economy, a gym membership you let expire, or a feature on your phone that you shut off by accident, when you reactivate something, you put it back into action.
In reactivate the prefix re- means "again." Added to the word activate, meaning "start," reactivate means "start again." If your email account has been shut down because of a password error, for example, you would contact tech support to reactivate it, or if you used to be part of a group that has stopped meeting, you might call the other members to see if they are interested in reactivating it, meaning start it back up.