Antivirus/ˈæntaɪvaɪrəs/ Definition 1 of 2Pro Tip 1/3Protective Software Antivirus often refers to software that guards against cyber threats, not just viruses. Her antivirus cleared out the spyware, not just viruses. Pro Tip 2/3Active Measures Antivirus can actively prevent threats; it doesn't just clean up after infection. The antivirus blocked the malicious website before it could do harm. Pro Tip 3/3Regular Updates Antivirus programs need updating to recognize new threats, implying ongoing action. After updating her antivirus, it caught the latest virus.