Wiktionary
beautifuller
a. (context obsolete English) (en-comparative of: beautiful)
Usage examples of "beautifuller".
The road laid peacefuller and beautifuller than ever, or so it seemed under the sunset glory that sort o' hung round it.
But if it's to be a flower-name, then I don't trouble about the length: it must be a beautiful flower, because, you see, I think she is very beautiful, and is going to be beautifuller still.