# insidiously

**Pronunciation:** /ɪnˈsɪdiəsli/ · in-SID-ee-us-lee

**CEFR level:** C2

**Part of speech:** adverb

## Meaning

In a manner that proceeds in a gradual, subtle way but with very harmful effects.

## Examples

- The disease progressed insidiously, showing no symptoms until it was already in an advanced stage.
- Political corruption began to work insidiously through the local government, slowly eroding public trust over several years.
- The software update insidiously tracked user data in the background without asking for explicit permission.

## Synonyms

- slyly — Suggests a clever or secretive manner, often for personal gain.
- stealthily — Emphasizes moving or acting without being seen or heard.
- treacherously — Implies a betrayal of trust or a hidden, dangerous threat.
- perniciously — Focuses on the destructive, long-term nature of the harm.

## Collocations

- insidiously undermine — The rumors began to insidiously undermine her confidence in the project.
- insidiously erode — The constant criticism started to insidiously erode their friendship.
- insidiously creep — Doubt began to insidiously creep into his mind as he waited for the results.

Canonical URL: https://anaversity.com/dictionary/english/insidiously

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