1. a romping girl, a tomboy; a mannish or masculine woman
...1848 Amer. dial.
2. a feminine young man; hence an effeminate (young) homosexual;
a prison catamite ...L19 sl.
"...who shies stones at them when they call her 'gal-boy,"
who drags her bonnet by one string..."
From: Lippincott's Magazine of Popular Literature and Science
Volume XXI. 1878
Small Farce and Comedy