Mammoth Uncensored Word List:
16 - 14 letter words starting with x

xanthochroisms xanthochromias xanthochromism xanthomelanous xanthophyllous xanthopterines xenodiagnostic xenophobically xenotransplant xerophthalmias xerophytically xeroradiograph xiphihumeralis xiphiplastrals xylopyrography xylotypography