birch ibrch brich rbich irbch ribch bicrh ibcrh bcirh cbirh icbrh cibrh brcih rbcih bcrih cbrih rcbih crbih ircbh ricbh icrbh cirbh rcibh cribh birhc ibrhc brihc rbihc irbhc ribhc bihrc ibhrc bhirc hbirc ihbrc hibrc brhic rbhic bhric hbric rhbic hrbic irhbc rihbc ihrbc hirbc rhibc hribc bichr ibchr bcihr cbihr icbhr cibhr bihcr ibhcr bhicr hbicr ihbcr hibcr bchir cbhir bhcir hbcir chbir hcbir ichbr cihbr ihcbr hicbr chibr hcibr brchi rbchi bcrhi cbrhi rcbhi crbhi brhci rbhci bhrci hbrci rhbci hrbci bchri cbhri bhcri hbcri chbri hcbri rchbi crhbi rhcbi hrcbi chrbi hcrbi irchb richb icrhb cirhb rcihb crihb irhcb rihcb ihrcb hircb rhicb hricb ichrb cihrb ihcrb hicrb chirb hcirb rchib crhib rhcib hrcib chrib hcrib
Note: these 'words' (valid or invalid) are all the permutations of the word birch. These words are obtained by scrambling the letters in birch.