Green’s Dictionary of Slang

ab n.2

also abb

(US drugs) an abscess that develops after injecting with an unsterile needle or an unsterile water/narcotic solution.

[US]B. Dai Opium Addiction in Chicago 196: Abb. Abcesses caused by bad drugs or dirty needles.
[US]D. Maurer ‘Lang. of the Und. Narcotic Addict’ Pt 2 Lang. Und. (1981) 98/1: ab. or abb. An abscess which forms in the arms or legs of conditioned needle addicts as a result of infections induced by impure drugs or unsterile needles.
[US]Monteleone Criminal Sl. (rev. edn).
[US]J.E. Schmidt Narcotics Lingo and Lore.
[US]E.E. Landy Underground Dict. (1972).