¹ Source: wiktionary.com
Definition of Penicillins
1. penicillin [n] - See also: penicillin
Medical Definition of Penicillins
1. A group of antibiotics that contain 6-aminopenicillanic acid with a side chain attached to the 6-amino group. The penicillin nucleus is the chief structural requirement for biological activity. A change in the nucleus will lead to a decrease in anti-bacterial activity. The side-chain structure determines many of the antibacterial and pharmacological characteristics. (goodman and gilman's the pharmacological basis of therapeutics, 8th ed, p1065) (12 Dec 1998)