# prophylactic

/ˌpɹɑfɪˈɫæktɪk/ (US) · /pɹˌɒfɪlˈæktɪk/ (UK) · CEFR C1 · Noun

Source: https://englishreference.com/word/prophylactic
Updated: 2026-10-12

## Definition

something used to prevent a disease or a problem before it starts. It is often used to talk about medicine or protection that keeps you healthy.

For teachers: a medicine or course of action used to prevent disease or unwanted consequences. Often used in medical contexts to refer to preventative treatments or devices.

## Examples

- The doctor prescribed a prophylactic to prevent infection.
- Regular exercise and a balanced diet serve as a prophylactic against many chronic health conditions.
- In public health, the distribution of clean water is the most effective prophylactic against the spread of waterborne diseases in developing regions.

## Synonyms

precaution, safeguard, contraceptive

## Usage notes

- Often used as a noun to refer to a specific preventative measure, but can also function as an adjective describing such measures.

---

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.