Of or relating to issues and practices not considered central to the Christian faith; adiaphorous. See adiaphoron . Also (occasionally) as noun: †an adiaphoron (obsolete).
Late 16th century; earliest use found in Thomas Newton (d. 1607), translator and Church of England clergyman. From post-classical Latin adiaphorus or its etymon ancient Greek ἀδιάϕορος indifferent + -al.