The term ‘heterodoxy’ refers to opinions or doctrines that are not in accordance with official or orthodox teachings.
The opposite of orthodoxy is heresy.
The word heterodoxy is often used of teachings considered to be erroneous when measured against orthodox beliefs, but not so erroneous as to be outright heretical. For example, most Protestant Christians consider many teachings of the Roman Catholic Church to be heterodox.
The word is derived from the Greek hetero = other, or different and doxa = to seem, to expect (interpreted as: common belief or popular opinion).