GamingReport reports that the as a noun. I would caution against getting too excited about this; every year, the OED committee adds a bunch of vogue words, and most of them get removed again in a year’s time. They mostly do this to get press attention. If I were handicapping, I’d allow that D&D has its long history as a concept, not just a brand, going for it, but I’d still say that its status as a corporate trademark argues against its long-term inclusion in the English language’s most authoritative dictionary. Sorry, kids.