The story
By humorous analogy with jockstrap, Jock and Jill being male and female names respectively.
Etymology from Wiktionary, CC BY-SA 4.0.
jillstrap
Today it means: A pelvic protector, a woman's equivalent of a man's jockstrap. Full definition →
Today it means: A pelvic protector, a woman's equivalent of a man's jockstrap. Full definition →
By humorous analogy with jockstrap, Jock and Jill being male and female names respectively.
Etymology from Wiktionary, CC BY-SA 4.0.