prophylactic

American  

[proh-fuh-lak-tik, prof-uh-] / ˌproʊ fəˈlæk tɪk, ˌprɒf ə- /

adjective

1. defending or protecting from disease or infection, as a drug.

2. preventive or protective.

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noun

1. Medicine/Medical. a prophylactic medicine or measure.

2. a preventive.

3. a device, usually a rubber sheath, used to prevent conception or venereal infection; condom.

prophylactic British  

/ ˌprɒfɪˈlæktɪk /

adjective

1. protecting from or preventing disease

2. protective or preventive

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noun

1. a prophylactic drug or device, esp a condom

Other Word Forms

• prophylactically adverb

Etymology

Origin of prophylactic

First recorded in 1565–75; from Greek prophylaktikós “of guarding,” equivalent to prophylak- (base of prophylássein “to guard beforehand”) + -tikos -tic; prophylaxis

Explanation

Prophylactic might sound like a prehistoric period when dinosaurs roamed the earth, but it actually describes something that can prevent something negative, such as disease. Prophylactic surgery to remove a mole can prevent skin cancer. If you want to avoid getting sick, you can get a vaccine, take medicine, or have surgery — all of which are considered prophylactic measures. Delve deeper into the history of this four-syllable word and you'll find the Greek term prophulaktikos, which means to "guard before." Prophylactic can also describe a contraceptive used to prevent pregnancy. This use of the word started because condoms, which are prophylactics, were originally designed to prevent disease, not pregnancy.

Example Sentences

Volunteers were divided into two groups: prophylactic arm and therapeutic arm.

From Science Daily • Feb. 19, 2026

It also announced plans to buy Cidara Therapeutics, which is working on antiviral treatments, including a flu prophylactic in Phase 3, for $9.2 billion.

From MarketWatch • Feb. 3, 2026

Third, these policies can serve an important prophylactic function by enabling employers to identify and remedy barriers to equal opportunity that, if allowed to fester, may lead to civil rights law violations.

From Slate • Feb. 10, 2025

"Regarding retention versus prophylactic extraction of asymptomatic wisdom teeth, decision-making should be based on the best evidence combined with clinical experience."

From Salon • May 7, 2024

Lastly, we have to speak of prophylactic measures, which really ought never to be thought of as a separate matter, but always as an essential and most important part of the treatment of neuralgia.

From Neuralgia and the Diseases that Resemble it by Anstie, Francis E.