How do you call the "happy-dog" part of file "happy-dog.png"?

I just realized I don't know how file is called in file.ext. The whole file.ext is called a file or filename, ext is called extension but how do you call the file part itself of file.ext? For example happy-dog.png. All the file/filename is happy-dog.png, extension is png but how do you call happy-dog? It's not basename. Is it like titlename? Or filepart? Any ideas?