6 letter words:
goniff13,
offing13,
5 letter words:
gonif9,
4 letter words:
goff11,
niff10,
figo8,
fino7,
foin7,
info7,
ingo5,
3 letter words:
iff9,
off9,
fig7,
fog7,
gif7,
fin6,
fon6,
gin4,
gio4,
gon4,
nog4,
ion3,
2 letter words:
if5,
of5,
gi3,
go3,
in2,
io2,
no2,
oi2,
on2,