Answer:
By breaking down the word and knowing what they mean separately, you can infer what the definition is as a whole. You know that ortho means correct and dox refers to opinion, so you can assume that the entire word's meaning is related to a "correct opinion".
The Oxford Dictionary definition of orthodox is: "(of a person or their views, especially religious or political ones, or other beliefs or practices) conforming to what is generally or traditionally accepted as right or true; established and approved." To put it simply, it means a teaching or statement that is true. (AKA a correct belief/opinion)
