Green’s Dictionary of Slang

1. to have sexual intercourse, esp. to impregnate a woman.

a.1593		Marlowe Ovid II 15: Then I that I may seal her privy leaves, Lest to the wax the hold-fast dry gem cleaves Would first my beauteous wench’s moist lips touch.
1594		Greene Frier Bacon and Frier Bungay D2: Ile [...] wed you heere, Then go to bed and seale vp your desires.
1616		Webster Duchess of Malfi V ii: I am like one That is condemn’d; I have my pardon promis’d, But I would see it seal’d.
1648		A Brown Dozen of Drunkards 14: [As Lusty Lawrence] waxeth wild with wine, he would seale all his obseane Letters with Virgins wax ... in this hot pot posture he will promise every maid marriage, and seale his promise if he can with his owne Image.
1719		in D’Urfey Pills to Purge Melancholy II 170: Like Lawyers deal, first Write, then Seal A little of one with t’other.
1890–1904		Farmer & Henley Sl. and Its Analogues.

2. (US black) to marry.

1935

M. Fulcher ‘Believe Me’ in Afro-American (Baltimore, MD) 25 May 5/1: There is no truth in the statement that Edith Scott was secretly sealed.