Your dog is absolutely stunning!
The definition out of a dictionary is going to vary from a scientific term. However, just like albinism there are different kinds of hybrids. Wolf Dogs for instance are often call Wolf Hybrids. However, this term is no longer used by Breeders or Scientists...
In the chicken world the term Hybrid is often used for describing mixed breeds. However, for scientific purposes you are correct hybrids are the crossing of mixed species usually resulting in infertile offspring