Xanthan, xanthate, xanthein, xanthene, xanthic, xanthin,
xanthine, xanthoma, xanthone, xanthous, xebec, xenia, xenic,
xenogamy, xenogeny, xenolith, xenon, xenopus, xerarch, xeric,
xerosere, xerosis, xerox, xerus, xi, xiphoid, xu, xylan, xylem,
xylene, xylidin, xylidine, xylitol, xylocarp, xyloid, xylol,
xylose, xylotomy, xylyl, xyst, xyster, xystos, and xystus. Not that
many.