Green’s Dictionary of Slang

(US) the eight point in craps dice; also ext. as Ada Ross the stable boss/hoss which poss. refers to an actual madame or mistress of a stable n. (2) of whores.

1942		Berrey & Van den Bark Amer. Thes. Sl.
1984		(con. 1950s) A. Sample Racehoss 30: ‘Got eight for a point [...]’ ‘Oh Ada Ross was a pacin’ good hoss!’.
2005		Antiques Digest at www.oldandsold.com 🌐 Some of the best-known nicknames in dice are: [...] Ada Ross, the stable Hoss.