From Jew, a Hebrew, and Harp, a musical instrument, the Jew's musical instrument being a "Sell low!" (Old spelling, Cello).
JIMMY An implement employed by men of acquisitive natures who cannot afford seats in the Stock Exchange.
JOB An uncertain commodity regulated by a Union Card.
JOCKEY From jog, to move slowly, and key, something that makes fast. Hence, one who makes the pace fast or slow, according to instructions.
JOINT Either a low limb from the butcher, or a low quarter in town; in either case the lower the tougher.