Undetected

Undetected is an adjective describing something not discovered or identified by a detection process. In everyday language it can refer to persons, phenomena, or signals that evade observation.

In science, detection involves methods to observe, measure, or identify a target. If a target remains undetected, it may be due to limited sensitivity, sampling gaps, noise, or deliberate evasion. In epidemiology, undetected cases (undercounting) occur when individuals harboring an infection are not captured by surveillance, leading to underestimates of prevalence or incidence. Seroprevalence studies or randomized testing can help uncover undetected infections.

In technology and security, undetected intrusions or evading detectors is often referred to as stealth or evasion. Cybersecurity uses concepts like undetected malware, zero-days, and stealthy backdoors; detection relies on signatures, anomaly detection, and behavioral analysis.

In astronomy and planetary science, undetected planets or objects may lie below the threshold of current instruments. Detection limits, survey completeness, and observational biases determine what remains undetected.

In criminology or forensics, a crime or suspect may remain undetected until evidence surfaces; in other contexts, “undetected” can describe contraband, fraud, or illicit activities that evade investigative methods.

Overall, the term underscores the gap between presence and observation, highlighting the role of method sensitivity, coverage, and thresholds in determining what is detected.