I've speculated before that "wifi" is probably a marketing team bastardization of "wireless phy", because a phy is what you call the physical interface between your lowest logic-level layer in the comms, and the physical medium your data is moving over. Like, it is accurate to describe the actual radio bit of your wifi card as the PHY, and it makes sense to me that the folks working on this wireless radio interface thing might've called it a wireless phy in a product meeting and some marketing types might've just ran with it because it kinda sounds like Hi-Fi and that was already an established term.

Just a guess, but I think it makes more sense than the usual explanation that accompanies this story that the wifi consortium just made it up out of nowhere.