X X chromosome X ray Xanax Xanthate Xanthelasma Xanthemia Xanthic acid Xanthine Xanthium Xanthoma Xanthoma disseminatum Xanthoma multiplex Xanthomatosis Xanthomonad Xanthomonas Xanthophyceae Xanthophyl Xanthophyll Xanthopsia Xanthorrhoeaceae Xanthorroea Xanthosis Xanthosoma Xanthosoma atrovirens Xanthosoma sagittifolium Xanthous Xantusiidae Xavier X-axis Xc Xci Xcii Xciii Xciv Xcl Xcv Xcvi Xcvii Xcviii Xe Xenarthra Xenicidae Xenicus Xenicus gilviventris Xenogeneic Xenogenesis Xenograft Xenolith Xenon Xenophanes Xenophobia Xenophobic Xenophon Xenopodidae Xenopus Xenopus laevis Xenorhyncus Xenorhyncus asiaticus Xenosauridae Xenosaurus Xenotime Xenotransplant Xenotransplantation Xeranthemum Xeranthemum annuum Xeric Xerobates Xeroderma Xeroderma pigmentosum Xerodermia Xerographic Xerographic copier Xerographic printer Xerography Xeroma Xerophile Xerophilous plant Xerophthalmia Xerophthalmus Xerophyllum Xerophyllum tenax Xerophyte Xerophytic Xerophytic plant Xeroradiography Xerostomia Xerotes Xerox Xerox copy Xerox machine Xestobium rufovillosum Xhosa Xi Xian Xii Xiii Ximenesia encelioides Xiphias Xiphias gladius Xiphiidae Xiphium iris Xiphoid process Xiphosura Xiphosurus polyphemus Xishuangbanna dai Xiv Xix Xizang Xl Xli Xlii Xliii X-linked dominant inheritance X-linked gene X-linked recessive inheritance X-linked scid Xliv Xlv Xlvi Xlvii Xlviii Xmas Xor circuit X-or circuit Xor gate X-radiation X-ray X-ray diffraction X-ray film X-ray machine X-ray photograph X-ray photography X-ray picture X-ray therapy X-ray tube X-raying X-scid Xt Xtc Xv Xvi Xvii Xviii Xx Xxi Xxii Xxiii Xxiv Xxix Xxv Xxvi Xxvii Xxviii Xxx Xxxi Xxxii Xxxiii Xxxiv Xxxv Xxxvi Xxxvii Xxxviii Xxy Xxy-syndrome Xy Xylaria Xylaria mali Xylaria polymorpha Xylariaceae Xylem Xylene Xylocaine Xylocopa Xylol Xylomelum Xylomelum pyriforme Xylophone Xylophonist Xylopia Xylopia aethiopica Xylose Xylosma Xylosma congestum Xyphophorus Xyphophorus helleri Xyridaceae Xyridales Xyris Xyris operculata Xyy