not genuine, counterfeit ...1803 sl.
from 'brum' - a native or inhabitant of Birmingham + -ish
First Documented Use: 1803
"When, besides having a handsome house over your head, the strange gentleman has left two guineas - though one seems light, and t'other looks a little Brummish - to be laid out for you, as I see occasion."
From: John Bull; or The Englishman's Fireside
By: George Colman