6 letter words:
ferret9,
5 letter words:
ferer8,
freer8,
freet8,
frere8,
refer8,
terfe8,
4 letter words:
feer7,
feet7,
fere7,
fete7,
free7,
fret7,
reef7,
reft7,
terf7,
tref7,
rete4,
teer4,
tree4,
3 letter words:
eft6,
erf6,
fee6,
fer6,
fet6,
ref6,
tef6,
ere3,
err3,
ree3,
ret3,
tee3,
2 letter words:
ef5,
fe5,
ee2,
er2,
et2,
re2,
te2,