oxacillin
noun
ox·a·cil·lin ˌäk-sə-ˈsi-lən 
: a semisynthetic penicillin administered in the form of its hydrated sodium salt C19H18N3NaO5S·H2O to treat infections caused by penicillin-resistant staphylococci
Example Sentences
Recent Examples on the Web The superbug is resistant to beta-lactam antibiotics, a broad-spectrum group which includes methicillin as well as oxacillin and the cephalosporins. 
Ranjit Devraj, Quartz India, 23 July 2019
Ranjit Devraj, Quartz India, 23 July 2019 Word History
Etymology
ox- + azole + penicillin
First Known Use
1962, in the meaning defined above
Medical Definition
oxacillin
noun
ox·a·cil·lin ˌäk-sə-ˈsil-ən
: a semisynthetic penicillin administered in the form of its hydrated sodium salt C19H18N3NaO5S·H2O to treat infections caused by penicillin-resistant staphylococci