Other forms: reconnected; reconnecting; reconnects
To fasten or join something together again is to reconnect. You can reconnect two pieces of model train track that have come apart — or reconnect with a friend you haven't seen in years!
When things that were previously connected detach from each other, they can sometimes reconnect. If you lose your internet connection in a windstorm, you may have to wait for the cable company to reconnect you. And if you track down your best friend from kindergarten and you may get to reconnect with him, reestablishing your relationship. In both cases, you're renewing a connection that had been lost.