Green’s Dictionary of Slang

cinquanter n.¹

a gambler.

1596		Nashe Saffron Walden 7: Some tall old cinquanter or stigmatical-bearded Master of Arts.
1617		Collins Defence Bishop Ely ii x 410: He would coniure you into a boote, or into a bench-hole for your labour, like a sawcy Sinckanter [OED].
a.1640		T. Jackson Creed x xix Works IX 115: One Volanerius an old sinkanter, or gamester and scurrilous companion by profession [OED].