5 letter words:
bourn7,
bruin7,
burin7,
burro7,
robin7,
4 letter words:
biro6,
birr6,
born6,
brin6,
brio6,
burn6,
burr6,
inro4,
iron4,
noir4,
nori4,
ruin4,
3 letter words:
bin5,
bio5,
bro5,
brr5,
bun5,
bur5,
nib5,
nob5,
nub5,
obi5,
orb5,
rib5,
rob5,
rub5,
urb5,
ion3,
nor3,
our3,
rin3,
run3,
urn3,
2 letter words:
bi4,
bo4,
in2,
no2,
nu2,
oi2,
on2,
or2,
un2,