In the December 1954 issue of Batman (#88), there’s a story written by Edmond Hamilton “The Mystery of the Four Batmen”, where the criminal is one of the “Batmen” on board a ship – a baseball player, achiropterologist (study of the flying mammals), and a pottery expert ( because of the “bats” used on pottery wheels), but it turns out that there’s a fourth “Batman”.
It turns out that “batman” is a unit of weight used in the Ottoman Empire (about 7 pounds 5 ounces). This undoubtedly came from Hamilton’s vast file of odd facts.
I didn’t learn until years later that “batman” means the servant of a commissioned officer in the British army. Neither, apparently, did Hamilton know it. (In one much later story, Alfred describes himself as “:Batman’s ‘batman’”)