theca hteca tehca ethca hetca ehtca thcea htcea tchea cthea hctea chtea techa etcha tceha cteha ectha cetha hecta ehcta hceta cheta echta cehta theac hteac tehac ethac hetac ehtac thaec htaec tahec athec hatec ahtec teahc etahc taehc atehc eathc aethc heatc ehatc haetc ahetc eahtc aehtc thcae htcae tchae cthae hctae chtae thace htace tahce athce hatce ahtce tcahe ctahe tache atche cathe acthe hcate chate hacte ahcte cahte achte tecah etcah tceah cteah ectah cetah teach etach taech atech eatch aetch tcaeh ctaeh taceh atceh cateh acteh ecath ceath eacth aecth caeth aceth hecat ehcat hceat cheat echat cehat heact ehact haect ahect eahct aehct hcaet chaet hacet ahcet cahet achet ecaht ceaht eacht aecht caeht aceht
Note: these 'words' (valid or invalid) are all the permutations of the word theca. These words are obtained by scrambling the letters in theca.