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

In mice, circulating levels of these metabolites remained high even after antibiotic treatment disrupted the microbiome.

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

Poop jokes and memes aside, cyclosporiasis is a serious parasitic foodborne intestinal illness whose symptoms include nausea, fatigue, and explosive diarrhea that can last weeks or even months without antibiotic treatment.

From Slate ● Jul. 22, 2026

The recommended treatment is a prescription antibiotic, sold under brand names including Bactrim or Septra, taken for seven to 10 days.

From The Wall Street Journal ● Jul. 17, 2026

Usually, a ten-day antibiotic treatment alleviates the symptoms, or a fast in-office medical procedure can release the pressure.

From "Endgame" by Frank Brady

Despite the promising results, the researchers stress that omega-3 and aspirin should not yet be viewed as a routine replacement for antibiotics in severe periodontitis.

From Science Daily ● Aug. 30, 2026

The fourth group received both approaches, taking antibiotics for two weeks while also following the omega-3 and ASA regimen for six months.

From Science Daily ● Aug. 30, 2026

King Harald V of Norway's health has worsened, the palace has said, as he remains in hospital receiving antibiotics for a bacterial infection in his bloodstream.

From BBC ● Aug. 24, 2026

Their associations with the gut microbiome were comparable to those seen with broad-spectrum antibiotics.

From Science Daily ● Aug. 24, 2026

Farmer was aware of what his critics would say: why blow $150,000 on antibiotics that, if you’d waited a while, would have cost you a fraction of that?

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

Related Words

• penicillin