Xanthochroic (a.)
definition: Having a yellowish or fair complexion; of or pertaining to the Xanthochroi.

Xanthochroic is a 12 letter word that begins with an X and ends in a C

Xanthogenate (n.)
definition: A salt of xanthic acid.

Xanthogenate is a 12 letter word that begins with an X and ends in an E

Xanthoxylene (n.)
definition: A liquid hydrocarbon of the terpene series extracted from the seeds of a Japanese prickly ash (Xanthoxylum pipertium) as an aromatic oil.

Xanthoxylene is a 12 letter word that begins with an X and ends in an E

Xenopterygii (n.)
definition: A suborder of fishes including Gobiesox and allied genera. These fishes have soft-rayed fins
And a ventral sucker supported in front by the pectoral fins. They are destitute of scales.
Xenopterygii is a 12 letter word that begins with an X and ends in an I

Xerophthalmy (n.)
definition: Xerophthalmia.

Xerophthalmy is a 12 letter word that begins with an X and ends in a Y

Xiphiplastra (pl)
definition: of Xiphiplastron

Xiphiplastra is a 12 letter word that begins with an X and ends in an A

Xiphisternum (n.)
definition: The posterior segment
Or extremity of the sternum; -- sometimes called metasternum ensiform cartilage ensiform process or xiphoid process.
Xiphisternum is a 12 letter word that begins with an X and ends in an M

Xiphisternum (n.)
definition: The xiphiplastron.

Xiphisternum is a 12 letter word that begins with an X and ends in an M

Xylobalsamum (n.)
definition: The dried twigs of a Syrian tree (Balsamodendron Gileadense).

Xylobalsamum is a 12 letter word that begins with an X and ends in an M

Xylophagides (n.)
definition: A tribe or family of dipterous flies whose larvae live in decayed wood. Some of the tropical species are very large.

Xylophagides is a 12 letter word that begins with an X and ends in an S

 1