Concept used to describe ways in which shitty social constructs like -isms & -phobias are interconnected (intersectional! geddit?) and not magically separate issues.
Also used to describe how social inequality is experienced as an "intersection" of several forms of discrimination.
For instance, feminism that totally ignores racism is inevitably going to fall flat on its face, and pretending all social issues boil down to "it's all about claaaaaass!" is an exercise in brainlessness.
A transsexual black woman experiences intersectionality because she experiences both transphobia, racism, and sexism.
People who cry "you're just being divisive! these are separate issues!" are ignoring intersectionality.
"My feminism will be intersectional or it will be bullshit."