From Wikipedia:
Etymology and terminology
The name Wi-Fi, commercially used at least as early as August 1999,[30] was coined by the brand-consulting firm Interbrand. The Wi-Fi Alliance had hired Interbrand to create a name that was "a little catchier than 'IEEE 802.11b Direct Sequence'."[31][32] According to Phil Belanger, a founding member of the Wi-Fi Alliance, the term Wi-Fi was chosen from a list of ten names that Interbrand proposed.[31] Interbrand also created the Wi-Fi logo. The yin-yang Wi-Fi logo indicates the certification of a product for interoperability.[33] The name is often written as WiFi, Wifi, or wifi, but these are not approved by the Wi-Fi Alliance.
The name Wi-Fi is not short-form for 'Wireless Fidelity',[34] although the Wi-Fi Alliance did use the advertising slogan "The Standard for Wireless Fidelity" for a short time after the brand name was created,[31][33][35] and the Wi-Fi Alliance was also called the "Wireless Fidelity Alliance Inc." in some publications.[36] IEEE is a separate, but related, organization and their website has stated "WiFi is a short name for Wireless Fidelity".[37][38] The name Wi-Fi was partly chosen because it sounds similar to Hi-Fi, which consumers take to mean high fidelity or high quality. Interbrand hoped consumers would find the name catchy, and that they would assume this wireless protocol has high fidelity because of its name.[39]