Comment by samatman

"daddy" is a kinship term, or familial title. It's a noun, and a mode of address, but it isn't a name, technically or otherwise. There are a few posts in this very thread about children realizing that "daddy" isn't just their father, but anyone's.

Much like when you refer to a doctor as "doc", or a professor as "professor".

To prove the point, there are people who have more than one person in their lives whom they call "Dad" or whatever variation. Raised by a gay couple, or close enough to a stepfather to think of him in those terms. Most of us only have one "Dad", but this isn't universal, and we all know that everyone has one, whether they refer to him that way, or even know him at all.