5 letter words:
butut7,
4 letter words:
burg7,
grub7,
brut6,
burr6,
butt6,
guru5,
trug5,
ruru4,
tutu4,
3 letter words:
bug6,
gub6,
brr5,
bru5,
bur5,
but5,
rub5,
tub5,
urb5,
gur4,
gut4,
rug4,
tug4,
rut3,
tut3,
utu3,
2 letter words:
gu3,
ug3,
ur2,
ut2,