The Origin of 'Puritan'

According to English Puritan Thomas Wilcox in a 1581 publication, it was Roman Catholic Nicholas Sanders who first coined the (intended-as) derogatory term 'Puritan'.

It thought by some that Catholic polemicists employed this term to 'taint' fervent Elizabethan Protestants with association to earlier groups referred to as Cathari (Greek katharos, pure, literally 'puritans'), including the Albigenses.