Green’s Dictionary of Slang

(UK Und.) winnings at crooked gambling, esp. through cheating at bowls and later cards.

1591		Greene Second Part of Conny-Catching in Grosart (1881–3) X 87: In Vincents Law. They which play booty, the Bankars. He that betteth, the Gripe. He that is coosened, the Vincent. Gaines gotten, Termage.
1608		Dekker Belman of London F3: The Gaines gotten is called Termage.
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue n.p.: The gains acquired, termage.