# vivo

/ˈvivoʊ/ (US) · CEFR C2 · Adjective

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

## Definition

taking place inside a living body, like a person or an animal, rather than in a lab dish. Scientists use this to describe tests done on real living things.

For teachers: occurring or performed within a living organism. Often used in scientific contexts to distinguish from experiments conducted in artificial environments; typically follows the preposition 'in'.

## Examples

- The researchers began in vivo testing on mice this week.
- While the drug worked well in a test tube, it failed to show the same results during in vivo trials.
- The complexity of systemic interactions often means that in vivo observations differ significantly from the simplified models seen in cell cultures.

## Usage notes

- Usually appears as part of the Latin phrase 'in vivo', which functions as an adjective or adverb. When used as an adjective before a noun, it is sometimes hyphenated.

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