ampicillin
noun
am·pi·cil·lin ˌam-pə-ˈsi-lən 
: a penicillin C16H19N3O4S that is effective against gram-negative and gram-positive bacteria and is used to treat various infections of the urinary, respiratory, and intestinal tracts
Example Sentences
Recent Examples on the Web Pregnant people who develop symptoms should also be treated with IV ampicillin, according to the American College of Obstetricians and Gynecologists (ACOG). 
Korin Miller, Health.com, 8 Dec. 2021 In their search, a few other antibiotics were associated with contraceptive failure in three or more case reports, including: ampicillin, amoxicillin, griseofulvin, metronidazole, and tetracycline. Korin Miller, SELF, 27 July 2017 The unidentified infant had contracted group B Streptococcus agalactiae (GBS) during birth and was given an 11-day course of ampicillin, according to a CDC newsletter, which detailed the case. Fox News, 30 June 2017
Korin Miller, Health.com, 8 Dec. 2021 In their search, a few other antibiotics were associated with contraceptive failure in three or more case reports, including: ampicillin, amoxicillin, griseofulvin, metronidazole, and tetracycline. Korin Miller, SELF, 27 July 2017 The unidentified infant had contracted group B Streptococcus agalactiae (GBS) during birth and was given an 11-day course of ampicillin, according to a CDC newsletter, which detailed the case. Fox News, 30 June 2017 Word History
Etymology
am(ino) + p(en)icillin
First Known Use
1961, in the meaning defined above
Medical Definition
ampicillin
noun
am·pi·cil·lin ˌam-pə-ˈsil-ən
: a penicillin C16H19N3O4S that is effective against gram-negative and gram-positive bacteria and is used in anhydrous forms, as the trihydrate, or as the sodium salt to treat various infections of the urinary, respiratory, and intestinal tracts see penbritin