Green’s Dictionary of Slang

1. (US black) any influential black man, a power in his own community, aged 30 and more.

1971

H.E. Roberts Third Ear n.p.: big daddy n. a person or friend with a good reputation; a respected person.

2. (mainly US black) one’s grandfather.

1955		T. Williams Cat on a Hot Tin Roof Act II: Big Daddy [...] threw down his fork.
1965–70		in DARE.

3. (US) a male lover, a sweetheart.

1953		L. Durst Jives of Dr. Hepcat (1989) 9: Miss Clawdy, he weight 440 and each and every pound is solid as a rock if you take a gander at Big Daddy you will most understand he’s sharper than Mr. Tack.
1960, 1975		Wentworth & Flexner DAS.

4. (US) a pimp.

1961

T.I. Rubin In the Life 155: Big Daddy: pimp or procurer, kept man.

5. (orig. US) an important person.

1964		in Current Sl. (1967) I:4 3/1: Big daddy, n. A leader.
1967		M. Braly On the Yard (2002) 70: The prisoner who held the power to regulate the traffic in inhalers would have to talk about it, floor show, and let it be known that he was Big Dad to all cotton freaks.
1969		D. Pendleton Executioner (1973) 151: You figure white-hair is the big daddy.
1986		R. Campbell In La-La Land We Trust (1999) 7: As long as you let him be big daddy, he’d make your life sweeter.
1989		G. Tate ‘The GOP Throws a Mammy-Jammy’ in Flyboy in the Buttermilk (1992) 106: While Atwater is certainly in a position to play Big Daddy, he doesn’t come off like that.
1995		J. Cameron Vinnie Got Blown Away 12: Hey this Big Daddy here, time to boogie.
2003		G. Tate Midnight Lightning 87: I didn’t really want to meet no other nigga, because by now I think I’m Big Daddy.

6. (US) the most important of its kind (not necessarily a human being).

1967		L. Bruce Essential Lenny Bruce 280: The Supreme Court’s the Big Daddy.
1989		M. Walker How to Kiss a Crocodile 110: Amongst the athletes, the Hawaiian Ironman is recognised as the big daddy of them all - the World Championship.

7. (US gay) the ‘masculine’ member of a homosexual couple.

1966		F. Elli Riot (1967) 174: Settle down there, Big Daddy [...] The queens are gettin’ along all right without you.
1972		B. Rodgers Queens’ Vernacular 110: Partner in a stable gay relationship who assumes the more dominant, masculine role [...] big daddy.

8. heroin.

1986

(ref. to 1972) in Spears Sl. and Jargon of Drugs and Drink 43: big daddy heroin [...] used in the movie $Dollars, 1972.