Cishet is a term used by LGBTQ+ people to easily describe people who are not members of the community in any way, shape or form. This means people who are simultaneously cisgender, heterosexual, and heteroromantic.
Exclusionists
Exclusionists have often used the term cishet to try to erase a-spec people from the community as the term implies that a-specs aren't LGBT+, making the term 'Cishetallo' preferable.