# vitro

/ˈvitɹoʊ/ (US) · CEFR C1 · Adjective

Source: https://englishreference.com/word/vitro
Updated: 2026-05-06

## Definition

happening in a lab or a test tube instead of inside a living person or animal. Scientists use this to test how things work in a controlled environment.

For teachers: occurring or performed in an artificial environment outside of a living organism, such as in a laboratory vessel or test tube. Often used in scientific research to isolate specific biological variables.

## Examples

- The scientists tested the new drug in vitro first.
- Before starting human trials, the researchers observed how the virus reacted to the treatment in vitro.
- While the compound showed significant promise during in vitro testing, it failed to produce the same therapeutic effects when introduced to complex biological systems in later stages.

## Usage notes

- Typically follows the preposition 'in' to form an adverbial or adjectival phrase; when used as an adjective before a noun, it is often hyphenated ('in-vitro').

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