7 letter words:
fripper14,
6 letter words:
ripper10,
5 letter words:
preif10,
prief10,
piper9,
firer8,
frier8,
rifer8,
prier7,
riper7,
4 letter words:
perp8,
pipe8,
prep8,
repp8,
ripp8,
fier7,
fire7,
reif7,
rife7,
peri6,
pier6,
ripe6,
3 letter words:
pep7,
pip7,
erf6,
fer6,
fie6,
fir6,
ref6,
rif6,
per5,
pie5,
pir5,
pre5,
rep5,
rip5,
err3,
ire3,
rei3,
2 letter words:
ef5,
fe5,
if5,
pe4,
pi4,
er2,
re2,