The term co-ed is short for co-education, which is a term that was coined when women were allowed to attend school with men. The term co-education is considered outdated by many and has been replaced with the terms mixed-education or mixed-gender education in many places.
Mixed is already a term with a long history of being used by professional sporting bodies to describe formats that include men and women. In tennis, there are mixed doubles. In Ultimate, the top divisions are split into Open, Women’s, and Mixed.
We believe that the term Mixed-Gender is more inclusive for people whose gender identities don’t fall into the man/woman binary construct.