Green’s Dictionary of Slang

barr n.

[manufactured by Barr Laboratories,]

(US drugs) the depressant benzodiazepine, e.g. Ativan, Halcion, Librium.

[US]N. Walker Cherry 219: I’d always been a lightweight when it came to the benzodiazepines. But I was broke and the barrs were the only drugs I had.