An antibacterial is a compound or substance that kills or slows down the growth of bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

The term is often used synonym
Synonyms are different words with almost identical or similar meanings. Words that are synonyms are said to be synonymous, and the state of being a synonym is called synonymy. The word comes from Ancient Greek syn and onoma . The words car and automobile are synonyms...

ously with the term antibiotic(s); today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic(s) has come to denote a broader range of antimicrobial
An anti-microbial is a substance that kills or inhibits the growth of microorganisms such as bacteria, fungi, or protozoans. Antimicrobial drugs either kill microbes or prevent the growth of microbes...

 compounds, including antifungal and other compounds.

The term antibiotic was coined by Selman Waksman
Selman Waksman
Selman Abraham Waksman was an American biochemist and microbiologist whose research into organic substances—largely into organisms that live in soil—and their decomposition promoted the discovery of Streptomycin, and several other antibiotics...

 in 1942 to describe any substance produced by a microorganism that is antagonistic to the growth of other microorganisms in high dilution.