ad ignorantiam
adverb (or adjective)
ad ig·no·ran·ti·am
¦ad-ˌig-nə-ˈran-shē-ˌam
: by use of unanswerable challenge to disprove rather than by serious attempt to prove
an ad ignorantiam argument
Word History
Etymology
Latin, to ignorance
First Known Use
1758, in the meaning defined above