For instance if I have two younger sisters, named Alice, and Becky, for example. How do I describe the sister who is not youngest, but the other younger sister?
Becky is my youngest sister. Alice is my next youngest sister? Least Young? Sister of penultimate youngness?
It gets worse if I have a third sister (Carly), whose age is between mine and Alice's. Now I need to refer to not only the sister who is older than Becky and Alice, but younger than I am.
Or is there no succinct way to express this? I tried to explain this concept to a French teacher once, but struggled to express it in English, and it's bothered me ever since.
Edit, to clear things up. I'm male. There's 3 sisters, and one brother.