@LiberalLibrarian I have a friend who is 18 years younger than her next youngest sibling and who has a nephew who is 10 months younger than she is. She introduces him as her cousin so she doesn't have to explain.
@divisionbyzero @LiberalLibrarian Of course we also referred to their parents as aunt and uncle, which they actually were. A bit complicated, really.
@divisionbyzero @LiberalLibrarian My mother has nieces and nephews who are only slightly younger than her. As kids, we always called them aunts and uncles, since they were pretty much our parents' generation.