“Drag”, in reference to cross-dressing, first appeared in the dictionary in 1870. The term originated, not surprisingly, in the theater. Men laden down in elaborate gowns heavy with jewels discovered a pitfall that every woman is familiar with – long hems tend to drag on the ground. As a result, when a male actor was required to dress as a woman, whether for a specific role or due to the lack of available performing females, the part was referred to as a “drag” role. As time went on, and cross-dressing moved offstage and into the general population, the term worked its way into common parlance.
A male who dresses in female clothing is referred to as a "drag queen," while a female who impersonates a male is a "drag king."