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

• 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

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

Prof Robin May, chief scientific officer at the UKHSA, says its analysis offers "strong reassurance that our existing vaccinations and antibiotic treatment offer will be effective against this strain".

From BBC • Mar. 24, 2026

Testing revealed the most common species was penicillium chrysogenum, famous because it is used to produce the penicillin antibiotic but it can cause allergic reactions or infections in people with compromised immune systems.

From BBC • Mar. 19, 2026

"So I hope people are reassured that we are managing it, antibiotic provision is there, we're standing up vaccination and general risk is low even if the disease itself is very serious."

From BBC • Mar. 18, 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

Related Words

• penicillin