Definition of illegal. : not according to or authorized by law : unlawful, illicit; also : not sanctioned by official rules (as of a game)
antibiotic. n. 1. (Pharmacology) 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. adj.
Antibiotics are medications used specifically to kill or disable bacteria. All bacteria are prokaryotic. organisms, meaning that their cells are different than cells of the human body. These differences can be exploited, so that antibiotic drugs can kill bacteria without harming us. Most of the bacterial world falls into one of two categories, Gram+ and Gram-, based on Article Summary: Antibiotics are drugs used to fight bacterial infections.