Green’s Dictionary of Slang

1. a fop, an affectedly showy person.

1618		Fletcher Loyal Subject IV ii: These are fine gimcracks: hey, here comes another, a Flagon full of wine in’s hand.
1818		‘Sir Gooseberry Gimcrack and Miss Squash’ in C.L. Fraser Chap Book (1920) Sept. 16: Sir Gooseberry Gimcrack was thin, / Like one of your neat dapper masters.
1821–6		‘Bill Truck’ Man o’ War’s Man (1843) 62: One of our gimcracks here, in a fine coat, who is of no use.

2. the penis .

1683

London Jilt pt 1 52: Limberham, though Impotent, caressed and embraced me so passionately [...] that I would have given all I had in the World that his Gimcrack had been in better condition.

3. a pert young woman.

c.1698		B.E. Dict. Canting Crew n.p.: Gimcrack, a spruce wench.
1705		S. Centlivre Basset Table Act II: The philosophical Gimcrack I don’t value of a Cockle-Shell.
1725		New Canting Dict. [as cit. c.1698].
1737, 1759, 1760, 1776		Bailey Universal Etym. Eng. Dict. [as cit. c.1698].
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
1811		Lex. Balatronicum.
1860		Hotten Dict. of Modern Sl. etc. (2nd edn) 148: GIMCRACK, [...] Old slang for ‘a spruce wench.’ — N. Bailey.
1873		Sl. Dict.

4. the female genitals.

1937–84

Partridge DSUE (1984) 463/2: C.19.