See the related link for a full list of words.
cacophony or Chemistry.
Duty has four letters and starts with a D, and ends with a Y.
Acceptability, admissibility and affordability begin with a and end with y. Applicability, assignability and attainability begin with a and end with y.
letters begins withf and y and if ends with letter m
naughty boy
One possibility is "mixed company".
Spy Try Fly Fry Sky Buy Dry Cry Wry Sly
Daylily
There do not appear to be any English 9-letter words that use those letters in any combination or amount.
A word that starts with y and ends with y is yay .
There are words that end with z and begin with most letters. However, there are no words in the English language that begin with y and end with z.
Anomaly, anarchy, anybody