antibiotic

American  

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

noun

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

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

Scientists refer to this as a Trojan horse effect, and the researchers say it may also play a role in the spread of antibiotic resistance.

From Science Daily • Jun. 6, 2026

The vitamin K shot is one of the three main interventions, along with the hepatitis B vaccine and an antibiotic ointment in the eyes, that newborns typically receive before leaving the hospital.

From Salon • May 7, 2026

And there was: There had been some progress, with oxytetracycline, OTC for short, a powerful antibiotic that is used to treat chlamydia and sometimes syphilis in humans.

From Slate • Apr. 20, 2026

This "selfless" sharing, known as horizontal gene transfer, can rapidly spread useful traits including genes that confer resistance to antibiotic drugs used to treat infections.

From Science Daily • Apr. 17, 2026

Roy removed a box of gauze, a roll of white adhesive tape, and a tube of antibiotic ointment that looked like barbecue sauce.

From "Hoot" by Carl Hiaasen

Related Words

• penicillin