Green’s Dictionary of Slang

abrahamer n.

also abramer
[var. on abraham-man n.]

a tramp.

[UK]H.T. Potter New Dict. Cant (1795) n.p.: abramers naked, ragged, dirty beggars, the lowest order of vagrants.
[UK]‘Jon Bee’ Dict. of the Turf, the Ring, the Chase, etc. 1: Abrahamers — a lot, or receptacle full of beggars, half naked, ragged and dirty. Vagrants.