antibiotic

American  

[an-ti-bahy-ot-ik, -bee-, an-tee-, -tahy-] / ˌæn tɪ baɪˈɒt ɪk, -bi-, ˌæn ti-, -taɪ- /

noun

• antibiotics
  plural

1. any of a large group of chemical substances, as penicillin or streptomycin, produced by various microorganisms and fungi, having the capacity in dilute solutions to inhibit the growth of or to destroy bacteria and other microorganisms, used chiefly in the treatment of infectious diseases.

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adjective

1. of or involving antibiotics.

antibiotic British  

/ ˌæntɪbaɪˈɒtɪk /

noun

1. any of various chemical substances, such as penicillin, streptomycin, chloramphenicol, and tetracycline, produced by various microorganisms, esp fungi, or made synthetically and capable of destroying or inhibiting the growth of microorganisms, esp bacteria

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adjective

1. of or relating to antibiotics

antibiotic Scientific  

/ ăn′tĭ-bī-ŏt′ĭk /

1. A substance, such as penicillin, that is capable of destroying or weakening certain microorganisms, especially bacteria or fungi, that cause infections or infectious diseases. Antibiotics are usually produced by or synthesized from other microorganisms, such as molds. They inhibit pathogens by interfering with essential intracellular processes, including the synthesis of bacterial proteins. Antibiotics do not kill viruses and are not effective in treating viral infections.

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1. Relating to antibiotics.

2. Relating to antibiosis.

antibiotic Cultural  

1. A substance that destroys or inhibits the growth of microorganisms and is therefore used to treat some infections. One of the most familiar antibiotics is penicillin.

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Discover More

Microorganisms that are initially treatable with antibiotics may evolve resistance as the more susceptible members of the population are killed off. (See resistance to antibiotics.)

Other Word Forms

Derived Forms

• antibiotically
  adverb

Inflected Forms

Nouns

• antibiotics
  plural

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Etymology

Origin of antibiotic

1855–60, for an earlier sense; anti- + biotic

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Explanation

An antibiotic is a substance used to kill bacteria. If you're coughing up green stuff, the doctor might give you an antibiotic to fight the infection. Since the prefix anti- means fighting, opposing, or killing, and bios is the Greek word for "life," antibiotic literally means life-killing. But doctors prescribe them primarily to kill the bacteria responsible for infections in the body. (A virus, on the other hand, cannot be treated with an antibiotic, so doctors are always making a distinction between a virus and a bacterial infection.) You can also use antibiotic as an adjective. Some plants have natural antibiotic effects when eaten.

Example Sentences

See Examples For:

antibiotic antibiotics

"You end up hunting for a decent length of antibiotic courses that will give you some relief," she said.

From BBC ● Oct. 13, 2026

"You're altering the microbiome of your gut, and perhaps creating antibiotic resistant bacteria in your body that will fight off the drug therapy the next time you really need it," he said.

From Barron's ● Oct. 8, 2026

The findings, published online Sept. 30 in the journal Nature, also showed that sugary diets combined with antibiotic treatment were associated with increases in Enterococcus faecium among patients.

From Science Daily ● Oct. 7, 2026

The findings therefore suggest that cutting back on simple sugars during and after antibiotic treatment could potentially reduce microbiome damage.

From Science Daily ● Oct. 7, 2026

Similarly, Marianne’s boyfriend lost his job as a roofer because he missed so much time after getting a cut on his foot for which he couldn’t afford the prescribed antibiotic.

From "Nickel and Dimed: On (Not) Getting By in America" by Barbara Ehrenreich

Chronic UTIs are infections where symptoms do not go away, and do not clear with a short course of antibiotics.

From BBC ● Oct. 13, 2026

For more frequent breakouts, they might prescribe higher-strength regimens such as antibiotics or medicines with tretinoin.

From Los Angeles Times ● Oct. 13, 2026

Some strains have developed resistance to multiple antibiotics and are responsible for difficult-to-treat infections acquired in hospitals.

From Science Daily ● Oct. 11, 2026

"Obviously it can be a very severe infection," he said, but he warned against taking a course of antibiotics without known exposure.

From Barron's ● Oct. 8, 2026

I’ve heard of prescriptions for antibiotics, but for machines?

From "Out of My Mind" by Sharon M. Draper

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Related Words

• penicillin

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