6 letter words:
reboot8,
5 letter words:
robot7,
4 letter words:
boet6,
boor6,
boot6,
bore6,
bort6,
broo6,
oboe6,
robe6,
root4,
rote4,
roto4,
tore4,
toro4,
3 letter words:
bet5,
boo5,
bor5,
bot5,
bro5,
obe5,
obo5,
orb5,
reb5,
rob5,
oor3,
oot3,
ore3,
ort3,
reo3,
ret3,
roe3,
roo3,
rot3,
toe3,
too3,
tor3,
2 letter words:
be4,
bo4,
ob4,
er2,
et2,
oe2,
oo2,
or2,
re2,
te2,
to2,