I went out for dinner to celebrate a birthday party last night and I actually heard this word in conversation. In fact I’ve heard it used at least three or four times in conversation in the last few years.
It means a fit of hysterical excitement or anger.
E.g. He was having conniptions!
North Americans, you should be proud to have produced such a wonderful word!
My aim is to use it in conversation at least once in the next six months.