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

Etymology

Origin of antibiotic

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

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

“It was like taking only one pill of your antibiotic regime,” says Rafael Simon.

From The Wall Street Journal ● Sep. 19, 2026

At the same time, metabolites made exclusively by microbes, including indole-3-propionate and p-cresol sulfate, declined after antibiotic treatment.

From Science Daily ● Aug. 15, 2026

There is an antibiotic available that is known to curb symptoms, which Clare heard has helped a friend.

From BBC ● Jul. 24, 2026

As antibiotic resistance grows around the world, the findings show that important medical advances may come from rethinking the chemistry of drugs that already exist.

From Science Daily ● Jul. 22, 2026

In a patient who gets only one antibiotic or inadequate doses of several, or who doesn’t take his medicine as instructed, the drug-susceptible bacilli may die off but the drug-resistant mutants will flourish.

From "Mountains Beyond Mountains" by Tracy Kidder and Michael French

A treatment of steroids, antibiotics, and a spray cleared up the rash in two weeks, Clive says.

From BBC ● Sep. 21, 2026

Professor Alastair Denniston, an ophthalmologist who also worked on the report, described the technology as "an exceptional opportunity" for healthcare which was "likely to rank alongside step-changes such as antibiotics and MRI".

From BBC ● Sep. 10, 2026

The doctor diagnosed her with laryngitis, external and prescribed antibiotics.

From BBC ● Sep. 5, 2026

A second group received the antibiotics metronidazole and amoxicillin.

From Science Daily ● Aug. 30, 2026

Low-cost second-line antibiotics would soon be on their way to Russia, but at the moment the supply chain wasn’t working.

From "Mountains Beyond Mountains" by Tracy Kidder and Michael French

Related Words

• penicillin