adj. combining necessary and scary
It is necesscary that you contact the IRS immediately regarding your reported income for tax years 2005, 2006 and 2007.
I had to figure out how to kill it before it killed me; it was necesscary.
That first jump from 10,000 feet was necesscary if I really wanted to skydive.
Adj- Bad information you don't want to know, but have to. Usually related to the diagnosis of a serious disease, car repairs, relationships, etc.
When my doctor told me I had colon cancer, I had to do some necesscary research on the subject.
It was necesscary moment when my mechanic told me what was wrong with my car.