The story
From (is)oxa(zole) + -cillin (“6-aminopenicillanic acid derivative”).
Etymology from Wiktionary, CC BY-SA 4.0.
oxacillin
Today it means: A narrow-spectrum beta-lactam antibiotic made by chemical modification of penicillin and administered in the form of its hydrated sodium salt C₁₉H₁₈N₃NaO₅S·H₂O to treat infections caused by penicillin-resistant staphylococci. Full definition →