You raise a super interesting question. Words change meaning over time– and sometimes the path to getting to current meaning matters for trademark law, but I don’t think it does here. Whether the word started out as as a descriptive word (e.g. “lite”) or a fanciful word coined just to be a mark (e.g. nylon, yo-yo, aspirin), the question for the court or PTO is what the word means now. I find the genus species test unusable in either case, but I really like the who are you/what are you test. Here’s why. Take “yoga.” Is it a genus including the different species of yoga, like Bikram, hot, ashtanga, flow, or is it a species of types of exercise? Either way, if I see that a studio is offering a yoga class, I know what the class is, but the term signals nothing about who offers it. So I find it much easier to classify this and most terms using that test.