To my mind right now, there is no word of your request.
asp
dew
emu eau ecu
Dud
One example of a three-letter word that starts with "a" and ends with "o" is "ago."
Dun. Something of an archaic term, thesedays.
niv
Lee
The
SPA
The only English words that fit those requirements are tee, the, tie and toe.
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