Actually I have never used this word for the clasp. Such an interesting contribution Bill, Thank you.
I remember in the seventies my father arguing about his friends with a jubilee bracelet on their Submariners. It was so anti-diver! His 6538 had a hollow-riveted, stretchable oyster bracelet (could have it been a 7206?) with a broken 78360 clasp (I do not know why). It could adjust over those amazing black-orange neoprene dive suits or just pull your hair out the wrist! The jubilees were of no use for such activities.