a synthetic antibiotic, CHNOS, derived from penicillin, having resistance to acids so that it can be taken orally to fight a wide range of bacterial infections
See ampicillin in American Heritage Dictionary 4
(ămˌpĭ-sĭlˈĭn)
noun
A semisynthetic penicillin having a broader antibacterial spectrum of action than that of penicillin G. It is effective against gram-negative and gram-positive bacteria and used to treat gonorrhea and infections of the intestinal, urinary, and respiratory tracts.