Xuanxue's vocabulary did not stay confined to commentary on the Laozi and the Zhuangzi. When Buddhist translators in the third and fourth centuries CE began rendering Indian philosophical vocabulary into Chinese, they had no existing technical language for concepts like sunyata, emptiness, so they reached for the nearest available Chinese terms already carrying philosophical weight, chiefly wu, non being, the very concept Wang Bi and He Yan had made central to Xuanxue's account of how the many things of the world depend on something that is not itself a thing. This practice, later called geyi, concept matching, let a monk explain an unfamiliar Buddhist idea by pairing it with a Chinese philosophical term the educated reader already understood.
The pairing was useful and misleading in roughly equal measure. Wu in Xuanxue names an ontological ground, the source from which being arises and on which it depends; sunyata in Buddhist philosophy names the absence of any fixed, independent essence in things that do exist, a claim about how things are rather than about a substance underlying them, and translators using wu risked making Buddhist emptiness sound like a Daoist first principle it was never meant to be. Later translators, Kumarajiva prominent among them, working from the early fifth century, moved away from geyi's borrowed vocabulary and toward more literal renderings answerable to the Sanskrit rather than to Xuanxue's own categories, but the earlier pairing had already done its work: readers who first met Buddhist philosophy through Xuanxue's borrowed words carried habits of reading emptiness as a kind of being that later, more careful translation spent generations trying to correct.