FWIW, N=1: I'm Dutch and don't recall the word "uitwaaien" being commonly used like this throughout society. It's only used in informal settings, e.g. between friends/family/colleague (AFAIK), and has little to no meaning outside specific contexts. It is, for instance, also used when joshing a person (with either teaseful or unpleasant intent) by proposing they should leave (the room or building): the phrase "ga jij maar even uitwaaien" means "(you should) go outside". When a cyclist informs a partner/friend/colleague about their intent to leave for (outdoor) cycling by saying "ik ga even uitwaaien". Hence I too am a bit surprised about this article.
"We’ve developed a method to assess whether a neural network classifier can reliably defend against adversarial attacks not seen during training [such as Elastic, Fog, Gabor, and Snow]. Our method yields a new metric, UAR (Unforeseen Attack Robustness), which evaluates the robustness of a single model against an unanticipated attack, and highlights the need to measure performance across a more diverse range of unforeseen attacks."
If anyone w/relevant expertise is willing to share thoughts on this: please do.
For further reading: this just in -> "Robust Machine Learning Algorithms and Systems for Detection and Mitigation of Adversarial Attacks and Anomalies: Proceedings of a Workshop" (2019) an open-access publication from the National Academies of Sciences, Engineering, and Medicine: https://doi.org/10.17226/25534.