The story
Probably from ef (“fluorine”) + -a- + -vir- (“antiviral”) + (b)enz(oxazinone).
Etymology from Wiktionary, CC BY-SA 4.0.
efavirenz
Today it means: A nonnucleoside reverse-transcriptase inhibitor C₁₄H₉ClF₃NO₂ that is administered orally with other antiretroviral agents in the treatment of type-1 HIV infection. Full definition →