Dad (dăd), n. [Prob. of Celtic origin; cf. Ir. daid, Gael. daidein, W. tad, OL. tata, Gr. ta`ta, te`tta, Skr. tāta.] Father; -- a word sometimes used by children.

"I was never so bethumped with words, Since I first called my brothers father dad." Shak.

-- Webster's unabridged 1913