Green’s Dictionary of Slang

1. a prostitute, a promiscuous woman.

c.1602		Shakespeare Troilus and Cressida V x: O traders and bawds, how earnestly are you set a-work, and how ill requited!
c.1622		ballad in Wardroper (1969) 135: Little Alice is found / Seven years to have been trader.
1629		Massinger Picture I ii: The night-trader I’ the streete, with certaine danger to the pocket.
1654		Mercurius Fumigosus 14 30 Aug.–6 Sept. 120: The PY-WOMEN in, next Bartholmow-Faire, from Bawde to Whore, and from Whore to Mob, and from Mob to Mort have such Rum trading, that Sodom and Gomorrah are now as empty of traders, as great Bedlam is of honesty.
1654		New Brawle 9: [I] kept two Beds going, and had as much resort to my House, early and late as the best trader of them all.
1660		Wandring Whore II 7: Many of these are new madams to me, but old Traders no question with others.
1683		Whores Rhetorick 219: A young Trader ought to be extreamly industrious to preserve her Face as long as she can.
1760		Foote The Minor 44: Tip him an old trader, and give her [i.e. a virgin] to the knight.
1818		W. Scott Heart of Mid-Lothian (1883) 201: She became a child of Belial, and a company-keeper, and a trader in guilt and iniquity.
1826		C.M. Westmacott Eng. Spy II 368: Meer Cyprian traders, captain, from the Gulf of Venus, engaged in gudgeon hawling, or on the look-out for flat fish.

2. an adulterer; a womanizer.

1640		R. Brathwait Ar’t Asleepe Husband? 62: [They] will never deale unlesse they shell Some hope of gaine, or like the Trader well.
1709		William Pen Turn’d Conjurer 7: An Apothecary who has a handsome Wife in his Shop, will not want for Customers, for many a young Spark will be Sick to be doing with her, and the more her Husband keeps out of the way, the more will her Traders creep in.

3. (US gay) a male homosexual prostitute.

1972

B. Rodgers Queens’ Vernacular 111: a male prostitute [...] trader.

4. (N.Z. prison) a prison drug dealer.

2001

D. Looser Boobslang [U. Canterbury D.Phil. thesis] 193/1: trader n. an inmate with a steady supply of drugs for sale to other inmates.