6 letter words:
burros8,
5 letter words:
burro7,
burrs7,
4 letter words:
bros6,
burr6,
burs6,
orbs6,
robs6,
rubs6,
sorb6,
urbs6,
ours4,
sour4,
3 letter words:
bos5,
bro5,
brr5,
bur5,
bus5,
orb5,
rob5,
rub5,
sob5,
sub5,
urb5,
ors3,
our3,
sou3,
2 letter words:
bo4,
or2,
os2,
so2,
us2,