antibiotic

IPA/ˌæntibaɪˈɒtɪk/
KK[ˌæntibaɪˈɑtɪk]IPA/ˌæntibaɪˈɑːtɪk/

antibiotic — noun

  • antibioticsingular
  • antibioticsplural

1. a drug used to fight infections caused by bacteria, by killing the bacteria or s

1.nounB2
Definition

a drug used to fight infections caused by bacteria, by killing the bacteria or stopping them from spreading inside the body — for example, penicillin given for a throat infection.

Example

Dr. Nikolai prescribed a five-day course of antibiotics for Tomás's chest infection.

collocation: prescribe a course of antibiotics

You should finish the whole course of antibiotics, even after you start feeling better.

collocation: finish the course of antibiotics

Common collocations
  • prescribe antibiotics
  • take a course of antibiotics
  • finish the antibiotics
  • broad-spectrum antibiotic
  • antibiotic resistance
Synonyms
  • antibacterial

    more technical; often used for products like soap or cleaners that kill bacteria

  • antimicrobial

    broader scientific term covering anything that kills bacteria, viruses, fungi, or parasites

Grammar Patterns

a course of antibiotics

take/prescribe antibiotics

Usage Note

Most often used in the plural (antibiotics) when talking about a treatment, even if only one drug is involved. Frequently appears with verbs like prescribe, take, give, finish, and complete.

Common Mistakes

I took antibiotic for my cold.
I took antibiotics for my chest infection.
antibiotics do not work on colds (which are caused by viruses), and the plural form is standard when describing treatment.

antibiotic — adjective

Word family

Synonym discussion

Sense: noun/1

All four words relate to fighting germs, but they are not the same. An 'antibiotic' is a medicine taken into the body (as a pill, liquid, or injection) to kill bacteria causing an infection — for example, penicillin for strep throat. 'Antibacterial' is a more general term, often used on consumer products like soap, hand gel, or wipes that reduce bacteria on surfaces or skin. 'Antimicrobial' is the broadest scientific term, covering anything that kills bacteria, viruses, fungi, or parasites; you'll see it on hospital coatings or modern fabrics. 'Antiseptic' refers to a substance applied to the skin or a wound to stop infection from starting — like the iodine a nurse paints on before stitches. So you take antibiotics, wash with antibacterial soap, and clean a cut with antiseptic.

antibiotic ↗antibacterial ↗antimicrobial ↗antiseptic ↗

Common collocations

Nouns

  • course of antibiotics
  • antibiotic resistance
  • antibiotic treatment
  • antibiotic cream
  • antibiotic ointment
  • broad-spectrum antibiotic

Phrases

  • finish a course of antibiotics
  • prescribe antibiotics
  • take antibiotics
  • develop antibiotic resistance

Prepositions

  • antibiotic for [an infection]

Etymology

GreekFrenchEnglish

Formed in early 20th-century English from the Greek roots 'anti-' meaning 'against' and 'biōtikos' meaning 'fit for life' (from 'bios', life). The word first described any substance produced by one living organism that harms another, but it became widely known after the 1940s, when penicillin and similar drugs began saving lives by killing infection-causing bacteria.