Some three letter words that end with "o" are:
Who?
who
too
One three letter word relating to anger and ending with O is ego.
oaf
Coo
ExpressoFalsettoFandango.
bingobravodittohippomottomangopestorodeotango
Some nouns that end with O are:avocadobanjobarriobongobuffalocargoDumboechoEggoegoflamingoGeoGeronimoghettogigolohaloherohoboJellokangaroolassoLOGOmangomojitomottonachoOhioOreopatiophotopianopiccolopotatoradiorhinosolostudiotacotangotattootomatotorpedotriovetovideovolcanoweirdoyo-yozerozoo
Do, no, so, to
Apollo
Arriero
gusto