6 letter words:
pruner8,
punner8,
runner6,
5 letter words:
prune7,
purer7,
unpen7,
rerun5,
4 letter words:
pern6,
puer6,
pure6,
purr6,
rurp6,
nurr4,
ruer4,
rune4,
3 letter words:
nep5,
pen5,
per5,
pre5,
pun5,
pur5,
rep5,
urp5,
ern3,
err3,
nun3,
nur3,
ren3,
rue3,
run3,
ure3,
urn3,
2 letter words:
pe4,
up4,
en2,
er2,
ne2,
nu2,
re2,
un2,
ur2,