Wi-Fi doesn’t stand for anything.
It is not an acronym. There is no meaning.
Wi-Fi and the ying yang style logo were invented by Interbrand.
We (the founding members of the Wireless Ethernet Compatibility Alliance, now called the Wi-Fi Alliance) hired Interbrand to come up with the name and logo that we could use for our interoperability seal and marketing efforts. We needed something that was a little catchier than ‘IEEE 802.11b Direct Sequence’. Interbrand created ‘Prozac’, ‘Compaq’ ‘oneworld’, ‘Imation’ and many other brand names that you have heard of.