Longman Dictionary of Contemporary English
Wiktionary
n. A man who founded something.
Wikipedia
"Founding Father" is a science fiction short story by Isaac Asimov. It was first published in the October 1965 issue of Galaxy Science Fiction, and reprinted in the 1975 collection Buy Jupiter and Other Stories. It was inspired by a cover painting of a space-helmeted face backed by several crosses, provided by the magazine's editor, Frederik Pohl.
Usage examples of "founding father".
The Amtrak Federation had come a long way since its founding father, George Washington Jefferson the 1st, had gathered the faithful Four Hundred around him and nursed them through the Long Night - the traumatic aftermath of the Holocaust.
Written into the contract by our founding father Jefferson was the assertion that if government violates the contract, the people have the right to overthrow it.
I felt the issue had been blown out of proportion and couldn't get that excited about it, but as a founding father I had quite a lot of respect amongst the people, and I knew I ought to be there.
In this case, though, my own title was The Last Tool, and once again the editorial change was for the better, so I kept FOUNDING FATHER.