fair sex, the

Girls or women, as in Many women would object to being called the fair sex nowadays. This euphemism uses fair in the sense of "physically beautiful" and is probably dying out. [Mid-1600s]

Females in general. This cliché, which is rapidly dying out, is a direct translation of the French le beau sexe, a phrase popularized by the English journalists Joseph Addison and Richard Steele (“That sex which is therefore called fair,” The Spectator, 1712). It was already a cliché by the time Arthur Conan Doyle (The Second Stain, 1905) put it in Sherlock Holmes’s mouth: “Now Watson, the fair sex is your department.”