The gender spectrum is an understanding that gender is not binary (female/male), but rather a spectrum of biological, mental and emotional traits that exist along a continuum.
In contrast, the gender binary—also called gender binarism or genderism—is a belief that gender is composed of two distinct and opposite genders (female and male) in which there is not overlap.
Unfortunately for those who believe in a gender binary, it is not scientifically or medically correct. Gender can’t be binary, because it is a personal identity and is socially constructed.
Sex—which refers to one’s biological characteristics—also exists as a spectrum, because intersex people exist.
Today, numerous scientific fields, including biology, endocrinology, physiology, genetics, neuroscience, and reproductive science, have confirmed that both sex and gender exist as a spectrum.
This is true for humans and across the animal kingdom.