# Unknown Unknown **Entity class:** Uncertainty category ## Definition An **unknown unknown** is a consequential actor, relationship, mechanism, assumption, or vulnerability absent from the current model. It becomes visible through anomaly, surprise, red teaming, adversarial testing, cross-domain synthesis, or evidence that existing hypotheses cannot explain. ## Relevance to this collection It connects [[wiki/Failure of Imagination|Failure of Imagination]], [[wiki/Threat Model Failure|Threat Model Failure]], [[wiki/Anomaly Detection|Anomaly Detection]], and [[wiki/Adversarial Adaptation|Adversarial Adaptation]]. ## Relationships - **master collection:** [[collections/Terrorism, Counterterrorism, and the Intelligence Environment|Terrorism, Counterterrorism, and the Intelligence Environment]]. - **convergence:** [[wiki/Counterterrorism-Cybersecurity Convergence|Counterterrorism–Cybersecurity Convergence]]. ## Sources / Provenance - [National Commission on Terrorist Attacks Upon the United States, *The 9/11 Commission Report*, July 22, 2004](https://www.9-11commission.gov/report/911Report_Ch11.htm). **As of:** 2026-09-23