Father.
"Daddy helped me tie my shoes before we went to school."
To father; to sire.
"The old oak tree will never daddy a new sapling, as it has died without producing any offspring."
One's father.
"The little girl ran to her daddy when she dropped her ice cream cone."
Daddy is a familiar form of dad that emerged when speakers added the diminutive suffix "-y." This affectionate nickname traveled into English to express endearment toward fathers.