The contemporary concept of “transgender” is based on the nuanced theoretical differences between biological sex and socialized performative gender roles; attempting to apply this contemporary distinction to historical actors has the potential to limit the depth and breadth of source material. A historical analysis of 20th century trans medicine must begin with an exploration of medical literature from the period to better understand how gender nonconformity was described, explained and approached as a medical condition. Unpacking the language systems surrounding the phenomenon of trans identity, particularly the language systems in medical literature, will demonstrate the way physicians and, thus, larger social communities understood those whose gender identity did not align with their anatomical sex.