In 1910, German sexologist Magnus Hirschfeld published The Transvestites: The Erotic Drive to Cross-Dress – the first investigation into the practice of wearing clothes designated for the “opposite” sex, and those who wanted to be the “opposite” sex or find space between “male” and “female”. With no recognised word to describe any of these positions or practices, Hirschfeld popularised “transvestite” from the Latin trans- (meaning “across”) and vestitus (“dressed”), variations on which had been used across Europe since the sixteenth century. (Zagria’s Gender Variance Who’s Who provides a potted history here.)
The sexological categorisation of gender-variant practices, and the new possibilities opened by scientific advances and changing attitudes throughout the twentieth century, posed a significant challenge to European languages, which had not previously been seriously demanded to accommodate areas between the two established sexes or genders. The definition of transvestite has been narrowed following the emergence of transsexual and genderqueer people, commonly referring to people who cross-dress for sexual pleasure without wishing for sex or gender reassignment, but a linguistic problem around gender variance that persists is that of pronouns – with just “he/him” and “she/her” in common English usage, little possibility traditionally existed for those between the gender binary, with third parties often unsure of how to address even those who have moved from male to female, or vice versa.