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, also known as antibacterials, are types of medications that destroy or slow down the growth of bacteria. The Greek word anti means against, and the Greek word bios means life (bacteria are life forms). Antibiotics are used to treat infections caused by bacteria.Bacteria are microscopic organisms, some of which may cause illness. The word bacteria is the plural of bacterium. Such illnesses as syphilis, tuberculosis, salmonella, and some forms of meningitis are caused by bacteria.he Greek word anti means against, and the Greek word bios means life (bacteria are life forms). Antibiotics are used to treat infections caused by bacteria. Bacteria are microscopic organisms, some of which may cause illness. The word bacteria is the plural of bacterium.