When you're detached or have lost your link to something (or someone), that's disconnection. If you live in Alaska and your family lives in Florida, you may feel a sense of disconnection.
There's emotional disconnection, when you're separated from people you care about, and there's also the disconnection that occurs when a cord is unplugged or a source of energy or information is broken. This kind of disconnection happens when you lose your internet connection or your game console isn't plugged into the TV. Disconnection adds the "not" prefix dis- to connection, which comes from the Latin connexionem, "a joining together."