6 letter words:
burger9,
5 letter words:
fugue9,
urger6,
4 letter words:
frug8,
fugu8,
berg7,
burg7,
grub7,
burr6,
rube6,
grue5,
guru5,
urge5,
ruer4,
3 letter words:
fub8,
fug7,
beg6,
bug6,
fer6,
feu6,
fur6,
ref6,
brr5,
bur5,
reb5,
rub5,
urb5,
erg4,
reg4,
rug4,
err3,
rue3,
2 letter words:
ef5,
fe5,
be4,
er2,
re2,