The author continues: "And how, exactly, is such a person to be defined?" The answer is in the article's own headline. "Gender-fluid" is a widely used term to define individuals who reject the gender binary to exist on a spectrum of gender identity. again, it's not clear whether they actually identify as gender-fluid (or if their intentions are to break past the gender binary) based on this Vogue profile. What it isn't is an appropriate term for a straight couple that sometimes swaps clothes, and using such a specific label to describe a seemingly gender binary-focused fashion trend is reductive, at best.