hydra yhdra hdyra dhyra ydhra dyhra hyrda yhrda hryda rhyda yrhda ryhda hdrya dhrya hrdya rhdya drhya rdhya ydrha dyrha yrdha rydha dryha rdyha hydar yhdar hdyar dhyar ydhar dyhar hyadr yhadr haydr ahydr yahdr ayhdr hdayr dhayr hadyr ahdyr dahyr adhyr ydahr dyahr yadhr aydhr dayhr adyhr hyrad yhrad hryad rhyad yrhad ryhad hyard yhard hayrd ahyrd yahrd ayhrd hrayd rhayd haryd ahryd rahyd arhyd yrahd ryahd yarhd ayrhd rayhd aryhd hdray dhray hrday rhday drhay rdhay hdary dhary hadry ahdry dahry adhry hrady rhady hardy ahrdy rahdy arhdy drahy rdahy darhy adrhy radhy ardhy ydrah dyrah yrdah rydah dryah rdyah ydarh dyarh yadrh aydrh dayrh adyrh yradh ryadh yardh ayrdh raydh arydh drayh rdayh daryh adryh radyh ardyh
Note: these 'words' (valid or invalid) are all the permutations of the word hydra. These words are obtained by scrambling the letters in hydra.