The prefix "eth-" is derived from the Greek word "ethos", which means character or habit. This prefix is commonly used in English as a part of words, mostly in the fields of ethics or moral philosophy, to denote a certain characteristic or trait. Examples include words like ethical, ethos, ethereal, and ethnocentric. However, there are several synonyms for this prefix that can be used interchangeably, such as moral, virtuous, righteous, and principled. These words carry similar meanings of having high morality or adhering to ethical principles. Whether it's "eth-" or one of its synonyms, all these terms ultimately relate to the importance of integrity and ethical behavior in one's life.