6 letter words:
infeft12,
5 letter words:
befit10,
feint8,
fient8,
4 letter words:
biff12,
fief10,
fife10,
niff10,
teff10,
tiff10,
feni7,
fent7,
fine7,
neif7,
nief7,
nife7,
bein6,
beni6,
bent6,
bien6,
bine6,
bint6,
bite6,
nite4,
tine4,
3 letter words:
eff9,
iff9,
fib8,
eft6,
fen6,
fet6,
fie6,
fin6,
fit6,
nef6,
tef6,
ben5,
bet5,
bin5,
bit5,
neb5,
nib5,
net3,
nie3,
nit3,
ten3,
tie3,
tin3,
2 letter words:
ef5,
fe5,
if5,
be4,
bi4,
en2,
et2,
in2,
it2,
ne2,
te2,
ti2,