Today, the term dragon is universally used for mythical, non-existent creatures that resemble dinosaurs in some ways. I thought I heard once from someone quoting a dictionary from 1600 something that the definition was "A very rare, but still living creature". This implies that the author thought that dragons were a real thing.
I don't expect there to be much overlap today from its ancient use because there is a lot of entertainment fiction written on the subject since 1900.
I want to know how the word has been used in the past and if there were descriptions of what a dragon actually is/was from before 1850's, when the word "dinosaur" was coined. I am also particularly interested if the people of those times thought the creatures were real.