ferer efrer freer rfeer erfer refer feerr eferr feerr eferr eefrr eefrr freer rfeer ferer efrer refer erfer erefr reefr eerfr eerfr reefr erefr ferre efrre frere rfere erfre refre ferre efrre frere rfere erfre refre frree rfree frree rfree rrfee rrfee errfe rerfe errfe rerfe rrefe rrefe feerr eferr feerr eferr eefrr eefrr ferer efrer freer rfeer erfer refer ferer efrer freer rfeer erfer refer eerfr eerfr erefr reefr erefr reefr frere rfere ferre efrre refre erfre frree rfree frree rfree rrfee rrfee ferre efrre frere rfere erfre refre rerfe errfe rrefe rrefe errfe rerfe ererf reerf eerrf eerrf reerf ererf erref reref erref reref rreef rreef eerrf eerrf ererf reerf ererf reerf reref erref rreef rreef erref reref
Note: these 'words' (valid or invalid) are all the permutations of the word ferer. These words are obtained by scrambling the letters in ferer.