4 letter words:
bors6,
bros6,
brus6,
burs6,
orbs6,
robs6,
rubs6,
sorb6,
urbs6,
ours4,
sour4,
3 letter words:
bor5,
bos5,
bro5,
bru5,
bur5,
bus5,
obs5,
orb5,
rob5,
rub5,
sob5,
sub5,
urb5,
ors3,
our3,
ous3,
sou3,
sur3,
2 letter words:
bo4,
ob4,
or2,
os2,
ou2,
so2,
ur2,
us2,