Green’s Dictionary of Slang

1. the vagina; often personified as Cecily Bumtrinket.

1600		Dekker Shoemakers’ Holiday I i: Silence Cisly Bumtrincket, let your head speake.
1607		E. Sharpham Cupid’s Whirligig III iii: Ile make her trusse vp her trinckets, oh faith she shall away.
1608		J. Day Law Tricks Act V: As for you, Sisley bumtrinkets, ile haue a bout with you at the single Stackado.
1641		R. Brome Jovial Crew Act II: Now bowse a round health to the Go-well and Com-well Of Cisley Bumtrincket that lies in the Strummel.
1654		E. Gayton Pleasant Notes II v 55: Up goes her trinkets too, sure as a gunne; / And when we have mortifi’d and tam’d the flesh, / We feed the stomacks good, as they that thresh. [Ibid.] 57: Many of her kindred are knowne by the names of Cicely Bumtrinket, Gillian of Winchester.
1728		Vanbrugh & Cibber Provoked Husband III i: If a Creditor be a little pressing, the Lady may be reduc’d, to try if instead of Gold, the Gentleman will accept of a Trinket.

2. a baby’s or small boy’s penis [note trinkets n. (1)].

1984

Partridge DSUE (8th edn) 1264/2: since ca. 1850.