5 letter words:
burgs8,
grubs8,
bruts7,
burst7,
trugs6,
4 letter words:
bugs7,
burg7,
grub7,
brut6,
burs6,
bust6,
buts6,
rubs6,
stub6,
tubs6,
urbs6,
gust5,
guts5,
rugs5,
trug5,
tugs5,
rust4,
ruts4,
3 letter words:
bug6,
bur5,
bus5,
but5,
rub5,
sub5,
tub5,
urb5,
gut4,
rug4,
tug4,
rut3,
uts3,
2 letter words:
us2,
ut2,