an·ti·bi·ot·ic 
(ăn′tĭ-bī-ŏtĭk, ăn′tī-)
(ăn′tĭ-bī-ŏtĭk, ăn′tī-)n.
A substance, such as penicillin or erythromycin, produced by or derived from certain microorganisms, including fungi and bacteria, that can destroy or inhibit the growth of other microorganisms, especially bacteria. Antibiotics are widely used in the prevention and treatment of infectious diseases.
adj.
1. Of or relating to antibiotics.
2. Of or relating to antibiosis.
3. Destroying life or preventing the inception or continuance of life.
an′ti·bi·oti·cal·ly adv.