Powassan encephalitis is a rare but potentially fatal disease caused by a virus that is transmitted through the bite of infected ticks. Some of the synonyms for Powassan encephalitis include tick-borne encephalitis and Powassan virus disease. While both of these terms are less commonly used than Powassan encephalitis, they describe the same condition and are recognized by medical professionals as valid alternative names for the disease. Other related terms that may be used in conjunction with Powassan encephalitis include arboviral encephalitis and tick-borne viruses, since the disease is caused by an arbovirus that is carried by ticks.