Green’s Dictionary of Slang

1. as a term of address; no affection is implied.

1927		(con. 1900s) S. Lewis Elmer Gantry 48: ‘I’ll explain how I feel.’ ‘Oh no, you won’t, sweetheart!’.
1939		E. O’Brien One Way Ticket 119: ‘Hello, sweetheart.’ Mac did not answer.
1944		R. Martin ‘Tea Party Frame-Up’ Mammoth Detective May 🌐 All right, sweetheart, we’re all through fooling.
1953		R. Chandler Long Good-Bye 295: ‘You got crossed up, sweetheart,’ Ohls told him carefully.
1960		G.W. Target Teachers (1962) 118: Just so long as we understand each other, sweetheart.
1978		J. Webb Fields of Fire (1980) 89: Don’t be sorry, sweetheart, just answer my goddam question.
1987		(con. 1967) E. Spencer Welcome to Vietnam (1989) 110: This is my time now, and you’re with me, sweetheart.
1993		J. Mowry Six Out Seven (1994) 191: Yeah, sweetheart, just one more sorry motherfucka in this great big sorry-ass motherfucker.
2001		M. Coles Bible in Cockney 13: The snake replied [...] ‘God ain’t gonna kill you, sweetheart.’.

2. a person; usu. used in a derog. sense.

1929		Hostetter & Beesley It’s a Racket! 240: sweetheart—Anyone you particularly dislike.
1937		C. Odets Golden Boy II iv: You’re a real sweetheart ...
1944		H. Hunt East of Farewell 49: He’s a sweetheart [...] So he’s got psychic powers now.
1953		R. Chandler Long Good-Bye 67: You didn’t spend three days in the freezer just because you’re a sweetheart. You got paid off.
1984		W. Diehl Hooligans (2003) 42: He favours a nine-millimetre Luger [...] A real sweetheart. He’s also a muscle freak.
1998		L. Stringer Grand Central Winter (1999) 69: ‘We’ve got a sweetheart of a judge out there,’ he beamed.

3. anything considered good.

1931		G. Milburn ‘Convicts’ Jargon’ in AS VI:6 441: sweetheart, n. Anything that is swell.
1950		Goldin et al. DAUL 216/2: Sweetheart. 1. One easily victimized; a place easily and profitably robbed. ‘That jug (bank) is a sweetheart for a pete-job (safe-robbery).’ 2. An extremely desirable person or thing.
1976		R. Daley To Kill a Cop 200: ‘It’s a sweetheart, that gun’.

4. (US Und.) a stolen automobile in good condition.

1949

Monteleone Criminal Sl. (rev. edn).