7 letter words:
pereion9,
pioneer9,
6 letter words:
opener8,
orpine8,
pereon8,
pernio8,
reopen8,
repine8,
5 letter words:
opine7,
orpin7,
preen7,
prion7,
prone7,
repin7,
ripen7,
irone5,
4 letter words:
neep6,
nope6,
open6,
peen6,
peer6,
pein6,
peon6,
pere6,
peri6,
pier6,
pine6,
pion6,
pirn6,
pone6,
pore6,
porn6,
pree6,
repo6,
ripe6,
rope6,
erne4,
inro4,
iron4,
noir4,
nori4,
rein4,
3 letter words:
nip5,
ope5,
pee5,
pen5,
per5,
pie5,
pin5,
poi5,
pro5,
rep5,
rip5,
eon3,
ere3,
ern3,
ion3,
ire3,
nee3,
nor3,
one3,
ore3,
ree3,
rei3,
rin3,
roe3,
2 letter words:
op4,
pe4,
pi4,
en2,
er2,
in2,
ne2,
no2,
oe2,
oi2,
on2,
or2,
re2,
