ortho rotho otrho torho rtoho troho orhto rohto ohrto horto rhoto hroto othro tohro ohtro hotro thoro htoro rthoo trhoo rhtoo hrtoo throo htroo ortoh rotoh otroh toroh rtooh trooh oroth rooth oorth oorth rooth oroth otorh toorh ootrh ootrh toorh otorh rtooh trooh rotoh ortoh toroh otroh orhot rohot ohrot horot rhoot hroot oroht rooht oorht oorht rooht oroht ohort hoort oohrt oohrt hoort ohort rhoot hroot rohot orhot horot ohrot othor tohor ohtor hotor thoor htoor otohr toohr oothr oothr toohr otohr ohotr hootr oohtr oohtr hootr ohotr thoor htoor tohor othor hotor ohtor rthoo trhoo rhtoo hrtoo throo htroo rtoho troho rotho ortho torho otrho rhoto hroto rohto orhto horto ohrto thoro htoro tohro othro hotro ohtro
Note: these 'words' (valid or invalid) are all the permutations of the word ortho. These words are obtained by scrambling the letters in ortho.