Wi-Fi is defined as an abbreviation for wireless fidelity, meaning you can access or connect to a network using radio waves, without needing to use wires.(abbreviation)
An example of Wi-Fi is when you go to Starbucks and can join on their network to get on the Internet without having to connect your computer to any wires.
See Wi-Fi in Webster's New World College Dictionary
Origin: < wi(reless) fi(delity), after hi-fi
See Wi-Fi in American Heritage Dictionary 4
Learn more about Wi-Fi