wildcat

A cruelly rapacious person.

An exploratory oil well drilled in land not known to be an oil field.

Any small or medium-sized cat resembling the domestic cat and living in the wild.

Without official authorization.

“wildcat work stoppage”

(of a mine or oil well) drilled speculatively in an area not known to be productive.

“drilling there would be strictly a wildcat operation”

“a wildcat mine”

Outside the bounds of legitimate or ethical business practices.

“wildcat currency issued by irresponsible banks”

“wildcat stock speculation”