X linkage
X-organ
X-ray
X-ray computed tomography
X-ray crystallography
X-ray diffraction
X-ray fluorescence
X-series recommendations
X.25
Xantho
Xanthophore
Xenobiotic
Xenoecic
Xenology
Xenoparasite
Xenophyophore
Xenotransplantation
Xeric
Xerographic recording
XFP
XHTML
Xiphoid
XML
XO
XT
XTE
Xylan
Xylem
Xylene
Xylose