Normally all the antivirus you use comes with their automatic definition downloading feature, so anytime they have an update and a good configured internet connection they automatically sync with their servers and grab that update download it and install it. But many times you might not have a well configured internet connection or your parents might have disabled your internet then how can you download updates for your antivirus.
Well now you can download then manually and carry them anywhere to update anyone's antivirus software. Well we are not doing this unofficially but its official and right from antivirus creator's website. So now mostly every good antivirus is covered in the below list so just visit yours and download the latest virus definitions.
Antivirus Definition Updates Download Sites
Well I have a list of 12 Antivirus update sites, so possibly you will find your antivirus in this list if not do comment I will post that one too.
Avast!– For Pro Antivirus and Internet Security Series [Link] AVG– Free version [Link] Internet Security & Premium Security [Link] Avira– Premium Antivirus and Internet Security [Link] Bitdefender– Antivirus, Internet Security and Total Security [Link] Comodo– Anti-Malware Database [Link] F-Secure– Antivirus Updates [Link] Kaspersky– Antivirus Updates [Link] Internet Security [Link] Pure Version [Link] McAfee– Antivirus Definition Updates [Link] Windows Defender– Antivirus Security Updates [Link] Symantec– Endpoint Protection and Antivirus Corporate Edition [Link] TrendMicro– Consumer, Enterprise and Mobile [Link] QuickHeal– Antivirus Updates for 2010, 2011, 2012 & 2013 [Link]
So guys these were the 12 Antivirus Software's for which you can manually download definition updates, if you find that your Antivirus is not listed do comment so that I can find a proper website for that one and post it out till then have fun :)