The full form of IPV5 is Internet Protocol Version 5

IPv5 is a version of Internet Protocol (IP) that was never formally adopted as a standard. The v5 stands for version 5 of the Internet Protocol. 

An internet protocol is the set of rules that govern how information packets are transmitted over a network. IPv5 is a version of Internet Protocol (IP) that was never formally adopted as a standard. The v5 stands for version 5 of the Internet Protocol. Computer networks use version 4, typically called IPv4, or a newer version of IP called IPv6.

IPv5 never became an official protocol. What is known as IPv5 started out under a different name: ​Internet Stream Protocol, or simply ST.

It would eventually serve as a foundation for the development of technologies like Voice over IP, or VoIP, which is used for voice communications over the internet.