A virucide (pronounced /ˈvī-rə-ˌsīd/ and alternatively spelled viricide and viruscide) is an agent (physical or chemical) that deactivates or destroys viruses. This differs from an antiviral drug, which inhibits the proliferation of the virus. A virucide (pronounced /ˈvī-rə-ˌsīd/ and alternatively spelled viricide and viruscide) is an agent (physical or chemical) that deactivates or destroys viruses. This differs from an antiviral drug, which inhibits the proliferation of the virus.