6 letter words:
bifter11,
5 letter words:
befit10,
brief10,
fiber10,
fibre10,
freit8,
refit8,
rifte8,
treif8,
biter7,
rebit7,
tribe7,
4 letter words:
frib9,
fier7,
fire7,
fret7,
frit7,
reft7,
reif7,
rife7,
rift7,
terf7,
tref7,
bier6,
bite6,
brei6,
brie6,
brit6,
rite4,
tier4,
tire4,
trie4,
3 letter words:
fib8,
eft6,
erf6,
fer6,
fet6,
fie6,
fir6,
fit6,
ref6,
rif6,
tef6,
bet5,
bit5,
reb5,
rib5,
ire3,
rei3,
ret3,
rit3,
tie3,
2 letter words:
ef5,
fe5,
if5,
be4,
bi4,
er2,
et2,
it2,
re2,
te2,
ti2,