Where chickens are concerned, I think you have nailed the word "hybrid" exactly.IDK if this is going to help or hinder, but in my mind the word hybrid is used in the chicken world to talk about crossing two specific breeds or types with predictable, reproducable results every time. If I put a Red rooster over a barred Rock hen, I'm going to get the same results no matter how often I do it, or what specific rooster and hen I use. Same for the red sex links, and the Cornish cross.
In my mind, this is what differentiates a hybrid from a plain old barnyard mix.