Daddy is an affectionate, informal word for father. Young children often say “daddy” instead of “dad” or “father,” especially when they're little. You might hear a three-year-old run to the door shouting “Daddy's home!” when their father arrives from work.

As children grow older, many switch to saying “dad,” though some people continue calling their father “daddy” throughout their lives, especially in certain regions like the American South. The word carries a warm, loving feeling that “father” (which sounds more formal) doesn't quite capture.

The word also appears in compound terms like granddaddy, meaning grandfather, or daddy longlegs, a spider-like creature with extremely long, thin legs. When someone says something is the granddaddy of them all, they mean it's the biggest, oldest, or most impressive example of its kind, like calling the Grand Canyon the granddaddy of all canyons.