Straight passing is a term used to refer to a queer or trans person in a duaric relationship, or a 'visibly straight' relationship. This can include asexual people, aromantic people, multisexual people, trans people and more. The term "straight-passing" is viewed as controversial, as it's used to undermine the validity of pan, bi, a-spec, or other people in m/w relationships such as straight trans people, and to argue why a-spec people specifically are not members of the LGBTQ+ community.
Another usage is for GNC, transgender and non-binary individuals in relationships that look straight due to presentation.