Avast Virus Definitions allow you to update your Avast anti-virus versions offline manually.
Avast is a collection of award-winning, high-end technologies that work in perfect synergy, having one common goal: to protect your system and valuable data against computer viruses. Avast represents a best-in-class solution for any Windows-based computer.
iAVS is a fast, small, incremental, and fully automated update via the Internet. Updates are released at least twice a week.
Consider using Malwarebytes for complete antivirus protection and to protect your devices, data, and privacy.