Green’s Dictionary of Slang

1. (US) a drug addict; dope addict.

1932		V.F. Nelson Prison Days and Nights 178: For every ‘D.A.’ (drug addict) who is listed, there are several who are unlisted.
1946		Mezzrow & Wolfe Really the Blues 304: Me card was stamped ‘D.A.’, which is short for dope addict.
1959		J.E. Schmidt Narcotics Lingo and Lore.

2. (orig. US) a duck’s ass, a style of haircut popular in the 1950s but still found.

1956		H. Ellison ‘Made in Heaven’ Deadly Streets (1983) 180: One of those half crew-cut, half d.a. haircuts.
1965		Ward & Kassebaum Women’s Prison 105: Ways of de-emphasizing femininity include close-cropped hair worn in a ‘D.A.’.
1978		A. Maupin Tales of the City (1984) 23: Her hair was done in a salt-and-pepper DA.
1982		(con. 1930s–50s) E. Mac Thomáis Janey Mack, Me Shirt Is Black 35: That other fella, ‘Teddy Boy’, who brought in the D.A. style – the duck’s arse.
1997		D. Farson Never a Normal Man 174: I walked up the hill with Teddy in his velvet collar and his hair carefully enticed into a D.A.
2004		N. ‘Razor’ Smith A Few Kind Words and a Loaded Gun 73: I got my hair cut in a quiff and DA (duck’s arse).

3. (US black) a term of contempt, a dog’s ass.

1971

(con. 1930s) D. Wells Night People 66: Shut up, d.a.!

4. (US campus) a fool, an idiot [dumb-ass n. (1)].

1975		G. Underwood ‘Razorback Sl.’ in AS L:1/2 57: DA n Dumb ass.
1978		S. King Stand (1990) 58: The fucking DA.