I think it is not his definition. The journalists use it for the new 2021 cars.
See:
https://www.autosport.com/f1/news/14484 ... t-for-2021
https://www.racefans.net/2019/07/17/ret ... vertaking/
What do we call them 2021 cars and their underlying bottom aero correctly?
twin diffuser cars? double venturi tunnel cars? wannabee wing cars?
Maybe we need a consensus here...
So that not every fan that is reading autosport.com etc. gets called for beeing clueless.
of racefans.net