Don't feel bad if you've never heard of a "gray rhino." The term wasn't used much before a 2016 book by Michele Wucker titled "The Gray Rhino: How to Recognize and Act on the Obvious Dangers We ...

Michele Wucker has defined a “gray rhino” as:. a highly probable, high impact yet neglected threat: kin to both the elephant in the room and the improbable and unforeseeable black swan.