The only thing that turned up at first online search is :

zyxt;
(obsolete, Kentish) second-person singular past tense of to see
[edit] TriviaThis word is notable for being the last word in the Oxford English Dictionary. The word was also used as a trade name by a soap manufacturer, presumably to suggest that it was the 'last word in cleanliness' (?)(?)

Retrieved from "http://en.wiktionary.org/wiki/zyxt"

The Collins ends with: Zyrian ; noun, the Finnic language spoken by the Komi [syn: Komi]