antibiotic

1 of 2

noun

an·​ti·​bi·​ot·​ic

ˌan-tē-bī-ˈä-tik,

-ˌtī-  -bē-ˈä- 

: a substance able to inhibit or kill microorganisms

specifically : an antibacterial substance (such as penicillin, cephalosporin, and ciprofloxacin) that is used to treat or prevent infections by killing or inhibiting the growth of bacteria in or on the body, that is administered orally, topically, or by injection, and that is isolated from cultures of certain microorganisms (such as fungi) or is of semi-synthetic or synthetic origin

Symptoms of campylobacteriosis include muscle aches, fever, cramps and diarrhea leading to gastrointestinal illness, which can be treated with antibiotics.

—Chicago Daily Herald

Another way to produce new variants of established antibiotics is to use genetic engineering to alter the biochemical pathways of the microbes that produce them.

—New Scientist

Experts agree that by spiking animal feed with antibiotics, conventional farmers are speeding the emergence of drug-resistant bacteria.

—Geoffrey Cowley

Note: While antibiotics are effective mainly against bacteria, they are sometimes used to treat protozoal infections. Some consider antibiotics to include only those derived fully or partly from microorganisms and exclude synthetic forms from this class of drugs.

antibiotic

2 of 2

adjective

1

: tending to prevent, inhibit, or destroy life

2

: of or relating to antibiotics or to antibiosis

antibiotic drugs

antibiotically

ˌan-tē-bī-ˈä-ti-k(ə-)lē

ˌan-ˌtī- 

-bē-ˈä-

adverb

Examples of antibiotic in a Sentence

Recent Examples on the Web

Noun

After three rounds of antibiotics, McEneaney decided to do exploratory surgery and ended up spotting a piece of hair out of the corner of his eye. —Angela Haupt, Time, 22 May 2025

Elissa ended up staying in the hospital for four nights as nurses and doctors waited for her fever to break, for the antibiotics to work, for her body to heal. —Kristen Jordan Shamus, USA Today, 19 May 2025

Adjective

People with an allergy to ceftriaxone would need an alternative antibiotic. —Md Published, Verywell Health, 6 May 2025

Notably, their work also includes research on the bacterium that causes gonorrhea, which has gained sudden urgency owing to the development in the U.S. of resistance to nearly every antibiotic used to treat the disease. —Atul Gawande, New Yorker, 21 Apr. 2025

Word History

Etymology

Noun

derivative of antibiotic entry 2

Note: Noun use of the adjective antibiotic probably began in the early 1940's, preceded by the frequent collocation antibiotic substance, but was not common before Selman waksman's paper "What Is an Antibiotic or an Antibiotic Substance?" (Mycologia, vol. 39, no. 5 [September-October, 1947]). Waksman has been credited with coining antibiotic, though he does not claim to have done so, and in fact gives an account of the earlier history of the word in this article.

Adjective

borrowed from French antibiotique, derivative of antibiose antibiosis (after symbiose symbiosis : symbiotique symbiotic)

Note: See note at antibiosis.

First Known Use

Noun

1943, in the meaning defined above

Adjective

1891, in the meaning defined at sense 1

Rhymes for antibiotic

• antipsychotic
• antithrombotic
• epizootic
• homoerotic
• psychoneurotic
• unpatriotic
• xenobiotic
• abiotic
• aeronautic
• apoptotic
• asymptotic
• cyanotic

Kids Definition

antibiotic

noun

an·​ti·​bi·​ot·​ic

ˌant-i-bī-ˈät-ik,

ˌan-ˌtī-,

ˌant-i-bē-

: a substance produced by an organism (as a fungus or bacterium) that in dilute solution inhibits or kills a harmful microscopic plant or animal and especially one that causes disease

antibiotic adjective

Medical Definition

antibiotic

1 of 2 adjective

an·​ti·​bi·​ot·​ic -bī-ˈät-ik; -bē- 

1

: tending to prevent, inhibit, or destroy life

2

: of or relating to antibiotics or to antibiosis

antibiotically

-i-k(ə-)lē 

adverb

antibiotic

2 of 2 noun

: a substance able to inhibit or kill microorganisms

specifically an antibacterial substance (as penicillin, cephalosporin, and ciprofloxacin) that is used to treat or prevent infections by killing or inhibiting the growth of bacteria in or on the body, that is administered orally, topically, or by injection, and that is isolated from cultures of certain microorganisms (as fungi) or is of semi-synthetic or synthetic origin

Note: While antibiotics are effective mainly against bacteria, they are sometimes used to treat protozoal infections. Some consider antibiotics to include only those derived fully or partly from microorganisms and exclude synthetic forms from this class of drugs.