5 letter words:
burrs7,
murrs7,
rubus7,
rurus5,
4 letter words:
bums8,
brus6,
burr6,
burs6,
murr6,
rubs6,
rums6,
smur6,
urbs6,
ruru4,
urus4,
3 letter words:
bum7,
brr5,
bru5,
bur5,
bus5,
mus5,
rub5,
rum5,
sub5,
sum5,
umu5,
urb5,
sur3,
2 letter words:
mu4,
um4,
ur2,
us2,