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

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

From BBC ● Jul. 24, 2026

When drug-resistant E. faecium was treated with both vancomycin and pghi-4, the antibiotic regained its ability to kill the bacteria.

From Science Daily ● Jul. 22, 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

For those who have fallen ill, treatment includes an antibiotic called Bactrim.

From Los Angeles Times ● Jul. 14, 2026

She ran her hands over the other things he had laid out: scissors, antibiotic ointment, bandages.

From "Bone Gap" by Laura Ruby

This can lead to severely painful episodes, which experts say can sometimes be prevented by wrapping up warm and drinking plenty of fluid, and daily antibiotics can reduce risk of infections.

From BBC ● Jul. 23, 2026

This is the idea behind antibiotic adjuvants, which are companion molecules that do not kill bacteria directly but instead restore the power of antibiotics.

From Science Daily ● Jul. 22, 2026

Luckily, the illness resolves with antibiotics, and it’s not fatal.

From Slate ● Jul. 17, 2026

Treatment generally involves antibiotics, according to the Cleveland Clinic.

From MarketWatch ● Jul. 14, 2026

He gives me antibiotics and hopes they’ll at least kill the infection I got from the intestinal sores.

From "Landscape with Invisible Hand" by M.T. Anderson

Related Words

• penicillin