# undetected

/ˌəndɪˈtɛktɪd/ (US) · /ˌʌndɪtˈɛktɪd/ (UK) · CEFR B2 · Adjective

Source: https://englishreference.com/word/undetected
Updated: 2026-05-11

## Definition

not noticed or discovered by anyone. You use this when something happens or exists without being seen or caught.

For teachers: not noticed, discovered, or identified by an observer or a technical system. Often used to describe errors, illnesses, or movements that escape attention.

## Examples

- The small error went undetected for several months.
- The virus remained undetected in the patient's system because it did not cause any obvious symptoms initially.
- Advanced stealth technology allows the aircraft to fly through enemy airspace undetected by traditional radar systems, providing a significant strategic advantage during reconnaissance missions.

## Usage notes

- Often follows linking verbs like 'go', 'remain', or 'stay'.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.