Doctor

Doctor was a title used by physicians and the holders of certain advanced university degrees. According to River Song, the term originated in the renegade Time Lord known as the Doctor. While the term originally meant "healer" or "wise man," some cultures used the word to mean "great warrior" due to their fear of the Time Lord known as the Doctor. It is implied that these cultures forgot the word's true origin. (DW: A Good Man Goes to War)