The word "wax" comes from old Sports cards. Until somewhere into the 90s, Packs of cards were enclosed in wax wappers --- hence the term, "wax." It is still used quite a bit in sports cards, so it's not a surprise the term gets applied to Magic cards.
Yes, if you collect baseball cards or the like, think Topps packs from 1983 or so. Not only were the packs made of wax, but they were sealed with wax too - they weren't like magic cards where the pack was crimped shut, but more like an envelope where the backside was folded and then sealed with wax (think letters in Medieval days).
anyway this is locked.