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.
antibiotic (anÂ´tibÄ«otÂ´ik) , n an organic substance produced by one of several microorganisms, especially certain molds, that is capable, in low concentration, of destroying or inhibiting the growth of certain other microorganisms.ntibiotic (anÂ´tibÄ«otÂ´ik) , n an organic substance produced by one of several microorganisms, especially certain molds, that is capable, in low concentration, of destroying or inhibiting the growth of certain other microorganisms.