Green’s Dictionary of Slang

capricorn v.

[Capricorn, the zodiacal sign of the Goat]

of a woman, to render her husband a cuckold.

[UK]R. Brathwaite Ar’t Asleepe, Husband? 84: A wily wench there was (as I have read,) / Who us’d to Capricorne her Husbands head.