Enter criteria and click Find Words
27 five letter words start with X, which makes it the smallest opening letter on the site by a wide margin.
Y takes about forty one percent and E thirty seven. Between them they are nearly four fifths of the list, and nothing else reaches eight.
XENON and XYLEM are scientific terms, XEBEC is a type of ship and XERIC means dry. Those are the entries with real definitions behind them.
XEROX is a company name that became a verb, and two entries are Roman numerals rather than words at all. The rest are Greek derived technical forms.
With a list this short and this technical, the page is more useful for confirming that you have read the tiles correctly than for finding an answer.
If an X really does sit in the first box, XENON is the most likely thing a puzzle would use.
X almost never begins an English root. Where it does, the word has usually come in from Greek, which is why the list reads as technical vocabulary.
It began as a company name and is now used as a verb in ordinary speech. Whether a puzzle accepts it depends on the word list behind that puzzle.
No. X sits in fewer five letter words than any other letter, so an early guess rules out almost nothing at all.