Junk term
A search term for something you do not sell at all. Pure waste, high confidence.
"Cast iron radiator" matching a skillet campaign. Off-category, no possibility of a sale, and easy to identify with confidence.
AutoPPC classifies and prioritises these because they are the safest negatives in the queue — the family check still runs, but there is rarely anything to protect. A sudden cluster of them is a junk burst, usually caused by an auto campaign's match loosening.