ignoratio elenchi

noun

ig·​no·​ra·​tio elen·​chi ˌig-nə-ˈrä-tē-ˌō-i-ˈleŋ-ˌkē 

: a fallacy in logic of supposing a point proved or disproved by an argument proving or disproving something not at issue

Word History

Etymology

Latin, literally, ignorance of proof

First Known Use

1588, in the meaning defined above