Mammoth Uncensored Word List:
20 words that are 13 letters long beginning with x in the mammoth uncensored word list.

xanthochroias xanthochroids xanthochroism xanthochromia xanthochroous xanthomatosis xanthophobics xanthopterine xanthopterins xenodiagnoses xenodiagnosis xerodermatous xerophthalmia xerophthalmic xiphiplastral xiphiplastron xiphisternums xiphophyllous xylobalsamums xylographical