Ethnos's rhymes with:
bonuses, cardenas's, catacosinos's, eyewitnesses, guinness's, illnesses, kotsonis's, likenesses, menaces, minuses, salinas's, selinas's, tennis's, witness's, witnesses'
Ethnos's sounds like:
eating, eaton's, eddings, eddins, edens, editing, edition's, editions, ethnic, ethnics, ethnos, euthanasia, euthanasia's, euthanize, eyewitness, eyewitnesses