Pronounced "jen-DER SPEC-trum."
Related terms include nonbinary, trans*, pansexual, gender expression.
"Angela self-identifies as pansexual because she's attracted to people on all parts of gender spectrum."
The term gender spectrum is a way of describing gender without conforming to the gender binary. It denotes gender as a continuum that includes male and female, but without establishing them as absolutes or polar opposites. The view of gender as a spectrum allows for the inclusion of identities besides male and female-- specifically, it allows for the inclusion of intersex people, nonbinary gender identities, and nonbinary gender expressions.
A person can fall anywhere on the gender spectrum regardless of their orientation, gender expression, or biological sex. For example, a heterosexual, cisgender (or cishet) woman might have a butch, tomboy, or androgynous gender expression. This does not mean that she does not identify herself as heterosexual or a woman, but it does subvert stereotypical ideas of womanhood based in gender binarism and gender essentialism.
The term gender spectrum has been used to some degree since at least the second-wave feminist movement of the 1970s, but has gained popularity as a component of the trans* acceptance movement beginning in the 1990s and continuing through today.