5 letter words:
opium9,
onium7,
4 letter words:
muni6,
muon6,
pion6,
upon6,
3 letter words:
imp7,
mop7,
pom7,
ump7,
mon5,
mun5,
nim5,
nip5,
nom5,
pin5,
piu5,
poi5,
pun5,
upo5,
ion3,
2 letter words:
mi4,
mo4,
mu4,
om4,
op4,
pi4,
um4,
up4,
in2,
no2,
nu2,
oi2,
on2,
un2,